JPH107425A - Material suitable for forming material requiring high accuracy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material suitable for a molding material which requirs high accuracy, for example, reflection surface for far infrared rays, far ultraviolet rays, laser, ultrasonic waves and the like, a mold for molding glass lenses, optical elements, resins, alloys, ceramic powder or the like and a mold for molding bearings and other slide members, optical discs and the like. SOLUTION: In a mold in which a functional layer is formed on a hard base material, a hard material in which a binder metal is not used is used as a mold base material and a hard layer made of, for example, SiC is formed on this mold base material through the plasma CVD technique. Subsequently, nitrogen ions are injected into this hard layer to form a mixed layer between the base material and the hard layer and form a diamond-like carbon(DLC) layer of high adhesion to the SiC layer. Since a binder-less superhard material is used as a base material, the SiC layer is prevented from surface-roughening caused by diffusion of elements of the iron group on molding. The mixing layer formed by injection of nitrogen ions between the base material and the SiC layer forms a chemically bonded layer between the base material and the SiC layer thereby increaasing the adhesion strength to the base material. Further, there occur nitrogen atoms having a larger atomic radius than that of carbon in the mixing layer and oxygen atoms are inhibited from diffusion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding surface for reflecting surfaces of far infrared rays, far ultraviolet rays, lasers, ultrasonic waves, etc., glass lenses, optical elements, resins, alloys, ceramic powders, etc.
Bearings and other sliding members, molds for molding optical disks, etc.
The present invention relates to a material which requires precision in shape and is suitable for forming a mirror surface.

[0002]

2. Description of the Related Art In recent years, a so-called direct molding method for molding an optical element material under high pressure with a mold in a molten state has been adopted as a molding means of an optical element.

[0003] As a material for the molding die, the hardness is high, the scratch is not easily damaged, the surface accuracy is good, and the oxidation resistance is excellent.
It is necessary that the heat resistance and the thermal conductivity are good, and as a mold component material that satisfies these required characteristics, there is a material in which the surface of a SiC sintered body is coated with a SiC film as a functional film by several hundred μm by a thermal CVD method. However, this is a mold material that is resistant to oxidation and is resistant to scratching. However, there is a problem in that it takes a long time to finish mirror finishing, and glass adheres to the surface of the mold even if the glass lens is pressed and formed as it is. is there.

Further, Japanese Patent Publication No. 5-40695 discloses that
Using a pair of molds in which a SiC film having a C / Si composition ratio of 0.7 to 1.2 is formed in a uniform thickness on a WC sintered body base material, in an inert atmosphere, at a softening temperature or higher. And press forming a heated glass material. This is Co
Is used as a bonding metal, and the bonding metal diffuses through the SiC film and adheres to the glass lens, making it unusable.
There is a local hardness difference, and there is a problem that the surface becomes rough with the use time, the adhesion strength of the SiC film is insufficient, and the glass peels off, and glass adheres to the SiC film.

Further, Japanese Patent Publication No. 5-40696 discloses that a mold material such as Al ₂ O ₃ , SiO _2
2 , via an intermediate layer of an oxide such as ZrO ₂ or TiO ₂ , α
-SiC and amorphous-SiC are disclosed.

When a film is formed on such a hard base material, interposing such an oxide intermediate layer has an effect as a barrier for preventing diffusion of oxygen from the glass to the base material side. By interposing such an oxide intermediate layer, this intermediate layer functions as a release film between the surface coating and the base material, and the adhesion strength between the SiC coating and the base material is insufficient, and the intermediate layer between the SiC film and the base material is insufficient. There is also a difference in the coefficient of thermal expansion between the layer and the substrate, and furthermore, oxygen diffuses from the intermediate layer to the substrate,
There is a disadvantage that the hard base material is oxidized and the surface of the mold is roughened.

Further, in the case of a superhard material whose base material has a general iron group element as a binder phase, since the glass lens is formed at a high temperature of about 700 ° C., the iron group element from the base material is formed during the forming process. And the surface of the mold may be roughened to roughen the mirror surface.

[0008]

The problem to be solved by the present invention is to improve the adhesion strength between the film and the substrate and the oxidation resistance of such a material having a functional film formed on a hard substrate. Another object of the present invention is to provide a material suitable for forming a member having high precision and an optical mirror surface in a short processing time.

[0009]

According to the present invention, after a hard film is provided on a base material made of a hard material not using a bonding metal, nitrogen ions are formed at an interface between the hard film and the hard film of the base material. An atomic level mixing layer is formed by implantation, and diamond-like carbon (DL)
C) A film is formed.

As a hard material containing no binding metal, A
l ₂ O ₃ —TiC-based material or Al ₂ O ₃ —SiC-based material or WC-TiC-TaC-based material, and furthermore, TiN, TiC, TiCN, NbC, NbC
A material substituted with any one or two or more of N, TaC, and TaCN, and a material having a WC or WC-TiC-TaC-based chemical vapor deposition film on its surface can be used.

The oxidation-resistant hard film is made of silicon carbide, silicon nitride, silicon carbonate, silicon carbonitride, titanium aluminum nitride, or an oxidation-resistant hard film formed of a composite film of two or more of these materials by plasma CVD, sputtering, ionization, or the like. Provided by plating or the like.

Further, after the diamond-like carbon film is formed by a plasma CVD apparatus or an ion plating apparatus, nitrogen ions or the like may be implanted from the surface in order to improve the adhesion strength. Also, when forming a diamond-like carbon film, nitrogen ions are implanted simultaneously with the film formation,
The adhesion strength between the diamond-like carbon film and the oxidation-resistant hard film can be improved. Similarly, the present invention can be used to improve the adhesion strength of the oxidation-resistant hard film to the mold substrate.

[0013] Among hard materials containing no binding metal, SiC
-CVD material, Si ₃ N ₄ than -CVD material a low hardness Al ₂ O _{3
-TiC, Al 2 O 3 -SiC,} WC-TiC-TaC -based material, TiC, a part or all of SiC or TaC, TiN, TiC, TiCN, NbC, NbCN, T
The material substituted by any one or two or more of aC and TaCN, and the material having a WC or WC-TiC-TaC-based chemical vapor deposition film on the surface is used to obtain an optical mirror surface. , it requires less processing time than those with base material Si ₃ N _4, or the like.

In the case of Al ₂ O ₃ or Al ₂ O ₃ —SiC based sintered material, when polishing with a diamond grindstone, Al ₂ O ₃ and TiC and Al ₂ O ₃ and SiC are mixed on the processed surface. Due to the difference in hardness, the roughness of the finished surface is likely to be a problem.
This is because iC and SiC are oxidized and changed to TiO2, SiO2, etc., and there is no problem of hardness difference, so that a surface with excellent polishing accuracy can be obtained. Since the transition metal bonding layer does not exist in the mold base, it is possible to prevent the mold surface from being roughened due to the diffusion of the iron group element into the SiC film during molding.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION When silicon carbide, silicon nitride, silicon carbonitride, and titanium aluminum nitride are coated on a hard base material containing no binding metal, oxidation resistance is improved, and SiC base material is coated with SiC by thermal CVD. It can be used for molding glass lenses at high temperatures in the same manner as the molded material.

The atomic-level mixing layer formed at the interface between the substrate and the film by the implantation of nitrogen ions forms a chemical bonding layer between the substrate and the film, and adheres the film to the substrate. Strength is improved. Even in a material having a small difference in thermal expansion coefficient between the hard material containing no bonding metal of the present invention and the oxidation-resistant hard film, if the energy of the ions is adjusted so that the vicinity of the interface is the average penetration depth of the ions, the interface is improved. Forming a so-called graded composition in which a mixing layer at the atomic level between the base material and the constituent elements of the film and nitrogen is formed, and the concentration of the implanted nitrogen atoms becomes smaller as the distance from the interface increases, thereby reducing the difference in thermal expansion coefficient. Can be. Furthermore, diffusion of oxygen is prevented in the mixing layer formed by nitrogen ion implantation at the interface between the hard film and the hard substrate containing no binding metal, because nitrogen atoms having an atomic radius larger than carbon are present. In addition, since the mixing layer with nitrogen ions is formed not only at the interface between the substrate and the film but also on the entire film, the diffusion of oxygen is prevented by the above-described effects, and the oxidation resistance of the mold substrate is improved. Then 700 °
A glass lens can be formed at a high temperature of C or higher. Here, nitrogen ions are used as the implanted ions. However, in consideration of chemical stability and damage to the film, boron, carbon, and oxygen may be implanted. However, oxidation resistance improves when boron ions are implanted. However, when boron diffuses into the film and comes out of the mold surface, it becomes B ₂ O ₃ and may adhere to the glass of the molding material. Further, when carbon ions are implanted, free carbon is formed in the film, and the oxidation resistance is reduced. When oxygen ions are used, a compound is formed at the interface between the mold substrate and the film, so that the adhesion strength is higher than that of the mixing layer at the interface due to inert gas ion implantation, but there is a problem with the oxidation resistance of the substrate due to diffusion of oxygen. There is. When nitrogen ions are used, a compound mixing layer is formed at the interface between the base material and the film as described above, and the bond strength is stronger than that when an inert gas ion is implanted, and when nitrogen is present in the film, diffusion of oxygen occurs. It has been found that the use of nitrogen ions is advantageous because it prevents

Further, by forming a DLC film on the above-mentioned hard film, a lens mold having excellent oxidation resistance and releasability as a whole mold can be obtained.

[0018] Although the reason for using a diamond-like carbon film as a release film, since carbon together in Microscopically the film is partially diamond bond (SP ₃ bond), high hardness Resistant to scratches and wear. Besides, at the time of molding,
At the outermost surface of this film, it changes to graphite which is chemically stable under the influence of heat at the time of molding, and hardly reacts with glass, and has excellent releasability. In addition, the surface of the diamond-like carbon film is depleted due to the reaction with oxygen in the glass or glass lens molding atmosphere. Does not occur.

[0019]

EXAMPLE An example in which the material of the present invention is applied to a lens forming die will be described.

As shown in Tables 1 and 2, Al ₂ O _3-
TiC ceramic, Al ₂ O ₃ -SiC ceramic,
WC-3wt% TaC, a kind of binderless carbide
One side of a substrate of φ30 mm × 5 mm made of a material obtained by coating a WC chemical vapor deposition film of 100 μm on the surface of a base material composed of −2 wt% TiC and WC-3 wt% Co is polished with # 2000 and # 8000 diamond grindstones. The surface was mirror-finished with a roughness of 7 nm at Rtm. Then, using a plasma CVD device or a sputtering device, a hard film made of silicon carbide, silicon nitride, silicon carbonate, silicon carbonitride, and titanium aluminum nitride, each of which is an underlayer, having a thickness of about 100 nm was formed on the mirror portion of these substrates. It was formed to become. For forming a silicon carbide, silicon nitride, silicon carbonate, silicon carbonitride, and silicon oxynitride hard film, SiH ₄ , CH ₄ , CO ₂ , NH ₃
Was used as a raw material and coating was performed using a high-frequency plasma CVD apparatus (13.56 MHz) at an output of 119.7 Pa and a pressure of 100 W. For example, in the case of silicon carbide, S
By changing the mixing ratio using iH ₄ and CH ₄ as raw materials,
The compositions of the films shown in Tables 1 and 2 can be obtained. Regarding the resulting films, those having a ratio of Si to C close to 1: 1 have good thermal stability, excellent oxidation resistance and high temperature. Showed high hardness. For silicon nitride, SiH ₄ and NH ₃ are used as raw materials, and for silicon carbonate, SiH ₄ , CH ₄ , CO ₂
, And SiH ₄ , CH ₄ ,
Using NH ₃ and CO ₂ as raw materials, and silicon oxynitride as SiH
₄ , CO ₂ and NH ₃ were used as raw materials. Although the composition ratio of each element in each film is set to 0.3 or more and 3 or less, it is not preferable that the composition ratio is smaller than 0.3 because the hardness decreases. On the other hand, if it is larger than 3, the adhesion strength to the diamond-like carbon film coated on this film increases, but the oxidation resistance decreases. Therefore, it is preferable to set it to 0.3 or more and 3 or less. For a titanium aluminum nitride film, a high frequency sputtering apparatus (13.56 MH) was used in a nitrogen atmosphere with TiAlN as a target.
z), with an output of 400 W using Ar ⁺ as a driving gas,
Coating was performed under the conditions of 0.665 to 1.33 Pa.

[0021]

[Table 1]

[Table 2] These hard films had the same mirror state as the substrate surface.

Further, from the direction perpendicular to the film, N ²⁺ accelerated to 140 keV was applied to 1 × 10
^It was implanted at a density of ¹⁴ to 1 × 10 ¹⁸ N + / cm ² . The surface roughness after implantation increases as the amount of implanted ions increases, and when it reaches 1 × 10 ¹⁸ N ⁺ / cm ² , the surface roughness Rtm becomes about 30.
0 nm. The injection amount at which the surface roughness of the hard film does not occur is 1 × 10 ¹⁵ to 1 × 10 ¹⁶ N + / cm ² , and the surface roughness is 10 nm in Rtm. In addition, the injection amount is 1 ×
If it exceeds 10 ¹⁵ N ⁺ / cm ² , the adhesion strength of the film becomes higher than the brazing strength, and in order to increase the adhesion strength of the film without causing the surface roughness of the film, the injection amount is 1 × 10 5 ^Fifteen
〜1 × 10 ¹⁶ N + / cm ² is preferable. In this embodiment, the case where the implantation amount of nitrogen ions is 1 × 10 ¹⁵ N ⁺ / cm ² is shown, but 1 × 10 ¹⁵ to 1 × 10 ¹⁶ N ⁺ / cm ^2.
The results were the same as those in Tables 1 and 2. In addition,
The adhesion strength of the film was measured by two methods, a scratch method and a pull-off method described below.

As a result of measuring the adhesion strength of each of the hard films before and after ion implantation with a scratch tester using a diamond cone, it was found that the adhesion strength was increased from 0.3N to 7N or more. In the peeling test using epoxy resin, SEBASTIAN V (made in the United States) was used.
It was found that those having only an adhesion strength of about 10 MPa before the ion implantation were broken by the epoxy resin after the ion implantation and did not peel off the film, and had an adhesion strength corresponding to a brazing strength of about 100 MPa or more. These samples were coated with a diamond-like carbon film of 100 nm using a hollow cathode type ion plating apparatus. The diamond-like carbon film was measured with a Raman spectrometer, and showed a spectrum that was higher at the position of the diamond peak wavenumber than at the position of the graphite peak wavenumber. The hardness was about 3900 in Vickers hardness. Although the adhesion of the diamond-like carbon film coated with a silicon carbide film is very high, the adhesion strength between the titanium aluminum nitride film and the diamond-like carbon film is not sufficient. After the formation of a diamond-like carbon film, nitrogen ions were implanted at 1 × 10 ¹⁵ N ⁺ / cm ² at an energy of 140 KeV to improve the adhesion strength. Then, 5000 glass goblets equivalent to SF5 were formed in an N ₂ atmosphere at a temperature of 700 ° C. and a load of 4.905 MPa, and the state of diffusion of oxygen was investigated by X-ray photoelectron spectroscopy. In the case of injection, oxygen was not diffused to the substrate, but in the case of not injected, the film was peeled or oxygen was diffused to the substrate, and the surface became rough. In the case where a diamond-like carbon film was directly formed on a binder-less carbide, 100 films were peeled off at the time of molding. When the mold before peeling of the film was examined by X-ray photoelectron spectroscopy, oxygen was diffused through the film in the substrate and oxidation of the substrate proceeded. A test was conducted to form a glass by forming a sample similar to the above for a substrate of WC-6 wt% Co having a shape of φ30 mm × 5 mm.
In this case, it was found that the mold surface became rough because Co of the binder phase diffused into the film. In addition, Co oozes out on the glass surface and affects the translucency of the glass. Thus, it is found that it is effective to use a hard base material such as the present invention which does not contain a bonding metal.

Note that part or all of TiC, SiC or TaC is converted to TiN, TiC, TiCN, NbC,
a material substituted with any one or more of bCN, TaC or TaCN and W instead of the WC chemical vapor deposition film
When a material coated with a C-TiC-TaC-based chemical vapor deposition film was used, the same results as in Tables 1 and 2 were obtained. The materials substituted with nitrides and carbonitrides in the above are advantageous because a material with a fine grain size can be obtained by the effect of suppressing grain growth and a material that can be easily processed to a surface roughness of the order of several angstroms is obtained. It is.

In the above, an example in which the material of the present invention is applied to a mold for forming a lens has been described. By taking advantage of the excellent properties of this material such as strength and corrosion resistance, and the ability to form a mirror surface, the above-described embodiment was used. In the manner described in (1), the present invention is not limited to a mold for forming a lens, but can be used for forming a reflecting surface such as a laser or an ultrasonic wave, or a mirror surface such as various sliding materials.

[0026]

According to the present invention, the following effects can be obtained.

(1) The adhesion strength of the functional film to the base material is increased, and the shortening of the life due to film peeling can be prevented.

(2) Due to the implantation of nitrogen ions, the diffusion rate of oxygen in the film is reduced, the oxidation resistance is improved, and the life of the super hard type is extended.

(3) When a SiC film is applied as a functional film of the type of the present invention, a DLC film having a coefficient of thermal expansion close to that of the SiC film is formed on the SiC film, so that the adhesion of the film is excellent.

(4) Compared to the SiC-CVD lens mold, the processing time for obtaining an optical mirror surface is shorter, and the coating of the oxidation-resistant hard film is excellent in oxidation resistance at a high temperature of 700 ° C. or more. Since the base material does not contain a binding metal, there is no diffusion of a transition metal element from the base material.

(5) Therefore, a glass molding material,
It can be suitably used for forming a reflecting surface such as a laser or an ultrasonic wave, or a mirror surface such as various sliding materials.

(6) In particular, when the material of the present invention is applied to a glass molding die, the DLC film has excellent mold releasability from glass, and the glass lens molded on the surface has a mirror-like state without fogging or roughness. Excellent products can be obtained.

Claims (6)

[Claims] After a hard film is provided on a base material made of a hard material not using a bonding metal, nitrogen ions are implanted into the hard film and an interface between the base material and the hard film to form an atomic level. A material suitable for a molded member requiring high precision, wherein a mixing layer is formed, and a diamond-like carbon film is formed thereon. 2. The hard material containing no bonding metal is Al ₂
O ₃ -TiC based material, Al ₂ O ₃ -SiC-based material, WC
TiC-TaC-based material or WC or WC-TiC-
2. The material according to claim 1, wherein the material is a material having a TaC-based chemical vapor deposition film on its surface. 3. An Al ₂ O ₃ —TiC-based material and WC-T
Part or all of TiC of the iC-TaC-based material is
N, TiCN, NbC, NbCN, TaC or TaCN
3. A material suitable for a molded member requiring high accuracy according to claim 2, wherein the material is replaced by one or more of the following. 4. A method according to claim 1, wherein part or all of the SiC of the Al ₂ O ₃ —SiC-based material is converted to TiN, TiC, TiCN, NbC,
The material suitable for a molded member requiring high precision according to claim 2, characterized in that it is a material substituted with one or more of NbCN, TaC and TaCN. 5. TaC in a WC-TiC-TaC-based material
A part or all of TiN, TiC, TiCN, N
3. The material suitable for a molded member requiring high precision according to claim 2, wherein the material is substituted with one or more of bC, NbCN, and TaCN. 6. The hard film is made of silicon carbide or silicon nitride or silicon carbonate or silicon carbonitride or titanium aluminum nitride.
The material suitable for a molded member requiring high precision according to any one of claims 1 to 5, wherein the material is composed of two or more of these multilayer films.