JPH0839361A - Member with diamond-tungsten composite film - Google Patents

Abstract

PURPOSE:To enhance the connecting strength of diamond crystal with tungsten and tungsten carbide, and improve the intensity of a composite film itself by enclosing the diamond crystal by metal tungsten and tungsten carbide. CONSTITUTION:A diamond crystal 1 consisting of at least one of diamond and diamond-like carbon is formed by CVD method on the surface of a base plate 8 consisting of silicon. At least one kind of metal tungsten and tungsten carbide is filled in the void in the diamond crystal 1 by CVD method to form a diamond-tungsten composite film 3 on the surface of the base plate 8. This diamond-tungsten composite film 3 is brazed to the base material of a member, and the base plate 8 of silicon is removed to provide a member with diamond- tungsten composite film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diamond-tungsten composite film-coated member, and particularly to a cutting tool for processing, industrial blades such as slitter knives, various sliding parts, thread paths, guide bushes and the like. The present invention relates to a diamond-tungsten composite film-coated member most suitable for wear-resistant members, parts for various measuring instruments, precision machining blades, medical instruments, various electronic elements, heat sinks for electronic parts, and the like.

[0002]

2. Description of the Related Art Ultra-hard materials such as diamond have hitherto been produced by a large-scale ultra-high pressure press machine. However, according to the vapor phase synthesis method (CVD), these materials can be obtained by a simple method, and therefore, ultra-hard materials such as diamond produced by the vapor phase synthesis method are expected to have a wide range of applications in the future ( See JP-A-60-54995).

However, an ultra-hard film such as diamond formed by CVD does not adhere to an iron-based alloy at all. Also,
Even a base material made of silicon nitride or cemented carbide has a problem that adhesion is insufficient and peeling easily occurs. Therefore, as a countermeasure against this, it has been proposed to form a diamond film on a silicon substrate, then remove the silicon substrate, cut out the diamond film and braze it to a base material made of a cemented carbide tool.

[0004]

However, in the method of directly brazing the diamond film to the base material, the wettability between the diamond and the brazing material (for example, Ag, Au-Sn, etc.) is low, so that the diamond film There is a problem that the bonding strength between the base material and the base material is low and, for example, the diamond film falls off from the base material in a short time. Further, in this method, since it is necessary to coat diamond thickly, there is a problem in that there are variations in the size of the crystal grains and there is a large variation in performance.

Therefore, if the diamond film and the base material can be firmly adhered to each other, the diamond film can be used in a wide range and improvement in performance can be expected. However, under the present circumstances, there is a limit to improving the adhesiveness with the base material as described above, and it is the current situation that the tools on which these ultra-hard films such as diamond are formed have not yet been put to practical use.

In addition, since it is necessary to form a thick diamond film, the cost for forming a thick diamond film (for example, power cost, equipment cost, time required for manufacturing) increases, and as a whole, it is conventional. No superiority over the method of directly forming the diamond film on the base material and the sintered diamond using the superhard pressure apparatus was recognized.

That is, an object of the present invention is to provide a diamond-tungsten composite film-coated member capable of improving the bonding strength with a base material.

[0008]

Means for Solving the Problems As a result of diligent studies on the above problems, the present inventors have found that among the metallic tungsten and the tungsten carbide formed by the CVD method in the voids between the diamond-like crystals created by the CVD method. The present invention has been found out that the bonding strength with the base material can be improved by brazing the diamond-tungsten composite film filled with at least one kind to the base material.

That is, the diamond-tungsten composite film-coated member according to the present invention is prepared by the CVD method in the voids between the diamond-like crystals made of at least one of diamond and diamond-like carbon. A diamond-tungsten composite film in which at least one of tungsten is filled is brazed to a base material.

Further, it is desirable that a bonding film made of at least one of metallic tungsten and tungsten carbide is interposed between the diamond-tungsten composite film and the base material.

Further, it is desirable that a dense film made of at least one of diamond and diamond-like carbon is formed on the surface of the diamond-tungsten composite film.

The diamond-like carbon in the present invention means
It means carbon which is very dense and has high hardness, no grain boundaries are observed, and a structure different from that of crystalline diamond having a regular crystal structure. Further, a diamond-like crystal composed of at least one of diamond and diamond-like carbon is produced by CVD (Chemical Vapor Deposition) and has voids between crystal grains, and its porosity is 5 to 5. 80%, and the film thickness is preferably 1 to 500 μm.

Further, according to the present invention, densification is achieved by filling the voids between the diamond-like crystals with metallic tungsten or tungsten carbide. still,
Examples of tungsten carbide include WC and W ₂ C.

As the base material for brazing the diamond-tungsten composite film, for example, WC, cobalt (Co), and carbides, nitrides, or carbonitrides of elements of groups 4a, 5a, and 6a of the periodic table are used. Made of cemented carbide or T
A cermet composed of iC or TiCN, nickel (Ni) or Co, and a carbide, nitride, or carbonitride of a group 4a, 5a, or 6a element of the periodic table, or silicon carbide (Si
C), a silicon carbide sintered body composed of boron and carbon, and S
It is composed of a silicon carbide or silicon nitride sintered body composed of i ₃ N ₄ or SiC and a rare earth element oxide. Further, the base material may be an iron-based alloy, a Ni-based alloy, a Co-based alloy, high speed steel, or the like.

Since diamond has a small coefficient of thermal expansion and poor wettability with other materials, it has poor adhesion to gas.
Furthermore, if a part of the diamond is carbonized at high temperature, the adhesion will be further reduced. Therefore, the bonding in a general plane is weak and may not be practically sufficient.

The diamond-tungsten composite film of the present invention comprises at least one of diamond and diamond-like carbon and at least one of metallic tungsten and tungsten carbide. The voids between the diamond-like crystals are filled so that metallic tungsten and tungsten carbide form a network structure in the cross section. The diamond-like crystals may be precipitated in a columnar shape or in a particle shape. FIG. 1 shows a mesh structure. As shown in FIGS. 2 and 3, a structure that forms a part of a mesh structure may be used. FIG. 4 shows a state in which gaps between columnar diamond-like crystals are filled with metallic tungsten and tungsten carbide. 1, 2, 3, and 4, reference numeral 1 is a diamond-like crystal, and reference numeral 2 is a metallic tungsten or tungsten carbide phase.

As described above, since tungsten and tungsten carbide wrap the diamond-like crystal,
The bonding strength between the diamond crystal and tungsten or tungsten carbide is improved, and the strength and toughness of the composite film itself can be improved. For example, a thickness of 0.5 m formed by the CVD method
When the three-point bending bending strength of the diamond film of m was measured to be 400 MPa, a diamond-tungsten composite film having a thickness of 0.5 mm in which metal tungsten was filled in the voids between the diamond-like crystals was used. Similarly, the bending strength was measured and found to be 600 MPa or more. Therefore, in the diamond-tungsten composite film of the present invention, properties such as strength can be improved over conventional diamond films, costs such as power consumption can be reduced, and the film formation time It can be significantly shortened as compared with the conventional diamond film. Further, with the conventional diamond film, only a small size film can be manufactured due to problems such as film forming time and cost, but a large size diamond-tungsten composite film according to the present invention can be manufactured.

Therefore, when a thick diamond-tungsten composite film is manufactured, the composite film itself is used as a cutting tool for processing, industrial blades such as slitter knives, various sliding parts, thread paths, guide bushes, etc. The wear resistant member, various measuring instrument parts, precision machining blades, medical instruments, various electronic elements, and electronic component heat sinks can be configured.

The diamond-tungsten composite film may be used by being bonded to the base material by a known bonding means (for example, an adhesive).

A diamond-tungsten composite film is provided with a reinforcing layer (for example, a layer made of at least one of tungsten and tungsten carbide). The cutting tool for processing, sliding parts, yarn paths, and wear-resistant members described above. , Parts for various measuring instruments, cutting tools for precision processing, medical instruments, various electronic elements, and heat sinks for electronic parts may be configured. In this case, the strength of the composite film can be improved by increasing the thickness of the reinforcing layer.

Further, it is desirable from the viewpoint of wear resistance and thermal conductivity to form a dense film made of diamond on the surface of the above composite film or the composite film having a reinforcing layer.

The diamond-tungsten composite film-coated member of the present invention comprises a diamond-tungsten composite film 3 brazed to a base material 4 as shown in FIG. As shown in FIG. 6, it is desirable that a bonding film 5 made of at least one of metallic tungsten and tungsten carbide be interposed between the material 4 and the material 4. A brazing material phase is formed between the base material 4 and the bonding film 5.

The thickness of the bonding film 5 is preferably 0.3 to 1000 μm. As the bonding film, tungsten carbide having a hardness higher than that of tungsten is desirable. The bonding film is preferably composed of a tungsten carbide layer on the composite film side and a tungsten layer on the base material side. This means that such a bonding film is a composite layer of a tungsten carbide layer and a tungsten layer. This is because the adhesion with diamond can be further improved. Further, such a composite layer generally has a fine structure and tends to have high strength, which is also advantageous from this point.

As shown in FIG. 7, on the surface of the diamond-tungsten composite film opposite to the base material, a dense film 7 made of at least one of diamond and diamond-like carbon is formed with a thickness of 0.2 μm or more. You may form. In this case, wear resistance and heat conductivity can be improved.

Then, as shown in FIG. 8, a bonding film 5 is formed between the diamond-tungsten composite film 3 and the base material 4, and the surface of the diamond-tungsten composite film 3 opposite to the base material 4 is formed. It is desirable to form the dense film 7 made of at least one of diamond, diamond-like carbon.

As shown in FIG. 4, the diamond-tungsten composite film-coated member of the present invention is manufactured on the surface of the substrate 8 made of silicon or the like by the CVD method, and is made of at least one of diamond and diamond-like carbon. Crystal 1 is formed, and this diamond crystal 1
At least one of metallic tungsten and tungsten carbide is filled in the space between the two by a CVD method to form a diamond-tungsten composite film 3 on the surface of the substrate 8, and the diamond-tungsten composite film 3 is used as a base material. It is performed by removing the substrate 8 made of silicon or the like by attaching it, or by removing the substrate 8 made of silicon or the like and then brazing the diamond-tungsten composite film 3 to the base material.

After the diamond-tungsten composite film 3 is formed on the substrate 8 made of silicon or the like, the bonding film 5 made of at least one of metallic tungsten and tungsten carbide is formed on the surface of the diamond-tungsten composite film 3. Then, after that, the bonding film 5 is brazed to the base material 4 to remove the substrate 8 such as silicon, or
After removing the substrate 8 such as silicon, the bonding film 5 is brazed to the base material 4.

[0028]

In the member with the diamond-tungsten composite film of the present invention, the tungsten and tungsten carbide wrap the diamond-like crystal, the bonding strength between the diamond-like crystal and the tungsten or tungsten carbide is improved, and the strength of the composite film itself is improved. The toughness can be improved.

When the diamond-tungsten composite film of the present invention is brazed to a base material, tungsten, tungsten carbide and a brazing material (eg Ag, Au-Sn, etc.) are used.
Since it has good wettability with, the bonding strength between the composite film and the base material is improved, and it can withstand long-term use.

Further, by interposing a bonding film made of at least one of metallic tungsten and tungsten carbide between the diamond-tungsten composite film and the base material, the bonding strength between the composite film and the base material is further improved. be able to.

Further, by forming a dense film made of diamond on the surface of the diamond-tungsten composite film, it is possible to improve characteristics such as wear resistance, thermal conductivity and hardness.

Since diamond, tungsten, and tungsten carbide have similar thermal expansion coefficients, internal stress in the composite film can be suppressed, and the production temperature of tungsten and tungsten carbide by the CVD method is low. The diamond will not decompose.

[0033]

The diamond-tungsten composite film-coated member of the present invention will be described in detail with reference to the drawings.

FIG. 5 shows the diamond-tungsten composite film-coated member of the present invention. The base material 4 is, for example, W.
It is composed of a compound consisting of C, cobalt (Co), and a carbide, nitride or carbonitride of elements of groups 4a, 5a and 6a of the periodic table.

The diamond-tungsten composite film 3 is brazed to the surface of the base material 4.

The diamond-tungsten composite film 3 is
As shown in FIG. 4, first, a diamond crystal is formed on the substrate 8 made of a known material by the CVD method. At this time, the substrate 8 on which these films are formed is formed of, for example, a metal such as silicon, carbon, or titanium, or a ceramic such as silicon nitride or silicon carbide, carbon, glass, or the like. The substrate 8 made of silicon is suitable because of the ease of nucleation in the initial stage of the film and the easy removal of the substrate 8 in the subsequent steps.

Known methods such as microwave plasma CVD, hot filament CVD, ECR plasma CVD, and plasma jet method are used for the film formation, but the nucleation density is lowered in at least a part of the steps to form a diamond-like crystal 1. It is important to create a gap between. To form such a diamond-like crystal 1, for example, EC
In the R plasma CVD method, a Si substrate is installed in the device,
A magnetic field having a maximum strength of 2 KG is applied, a microwave output of 3 to 5 KW, a substrate temperature of 700 ° C. or less, and an apparatus pressure of 0.
It is obtained by forming a film under the conditions of 05 to 0.5 Torr. CH ₄ , CO ₂ and H ₂ were used as reaction gases,
The concentration of methane shall be 5% or less. Further, a film having a gap can be formed by adjusting the substrate temperature, the amount of introduced gas, and the pressure in the furnace.

Further, the thickness and crystal structure (ratio of pure diamond or diamond-like carbon) of the porous film composed of the diamond-like crystals 1 can be arbitrarily selected depending on the substrate temperature, the gas concentration and the like. In consideration of the balance between performance and productivity, the diamond-tungsten composite film 3 has a thickness of 0.
3 to 100 μm is suitable.

Incidentally, after a dense diamond film is first coated by a known method, the grain boundaries of diamond may be etched to form a gap. Although various methods are used for etching, for example, a dense diamond film formed on a Si substrate is O ₂ 100%, 0.1 Torr.
r, installed in ECR plasma with microwave output of 1 kW and etched for 30 minutes. Even if another coating method is used, if a minute diamond film or a mixed film of diamond and diamond-like carbon is formed by coating, a small amount of oxygen or oxidizing gas (CO ₂ etc.) is introduced into the furnace. , The grain boundaries of diamond or diamond-like carbon are selectively etched, and a film having gaps between particles can be formed.

It is also possible to first coat a dense diamond film by a known method and then change the coating conditions to form gaps between the particles. In this case, the dense film of the present invention can be formed on the surface of the composite film.

Then, as shown in FIG. 4, the CVD is performed in the gap between the diamond-like crystals 1 produced as described above.
To fill tungsten and tungsten carbide 2.

To fill the tungsten, a known method used for forming a tungsten film can be used. For example, an example of filling the gaps between the diamond-like crystals 1 with tungsten will be described. The substrate 8 having the diamond-like crystals 1 formed thereon is housed in a chemical vapor deposition (CVD) apparatus, and the chemical vapor deposition is performed. Temperature in the device is 250-12
WF ₆ + H mixed at the temperature of 00 ℃
By introducing ₂ gases, the gaps between the diamond-like crystals 1 are filled with tungsten. An inert gas such as Ar gas or He gas may be introduced together with the WF ₆ + H ₂ gas. To fill the gaps in the diamond-like crystal 1 with tungsten carbide, the gas of H ₂ and WF ₆ and methane,
A carbon source gas such as acetylene or benzene is introduced into the reactor.

Next, the diamond-tungsten composite film 3 is masked, and the substrate 8 made of silicon or the like is dissolved and removed with an acid or the like. The base 8 may be mechanically peeled off.
Thereby, the diamond-tungsten composite film 3 is obtained. Next, cut this into a predetermined shape with a laser etc.,
After that, as shown in FIG. 5, the diamond-tungsten composite film 3 is brazed to the base material 4 by silver brazing or another brazing material and joined. After the brazing is finished, final processing is performed to obtain the diamond-tungsten composite film-coated member of the present invention. The substrate such as silicon may be removed after brazing the diamond-tungsten composite film 3 to the base material 4.

In the member with a diamond-tungsten composite film constructed as described above, tungsten and tungsten carbide wrap the diamond-like crystal 1,
The bonding strength between the diamond crystal 1 and the tungsten 2 is improved, and the strength and toughness of the composite film 3 itself can be improved. In addition, since the wettability between the tungsten or tungsten carbide 2 and the brazing material (for example, Ag, Au—Sn, etc.) is good, the bonding strength between the composite film 3 and the base material 4 is improved, and it can be used for a long time. Can bear.

Moreover, since diamond, tungsten, and tungsten carbide have similar thermal expansion coefficients, the internal stress of the composite film 3 can be suppressed, and diamond is decomposed because the production temperature of tungsten and tungsten carbide is low. There is nothing to do.

Another embodiment of the present invention will be described with reference to FIG.

FIG. 6 shows a member with a diamond-tungsten composite film according to the present invention, in which the diamond-tungsten composite film 3 and the base material 4 are joined together by at least one of metallic tungsten and tungsten carbide. Membrane 5 is interposed.

The bonding film 5 is formed as follows. First, the diamond formed on the surface of the substrate 8
A film made of at least one of tungsten and tungsten carbide is formed on the tungsten composite film 3. A known method can be used for the film formation. For example, to describe an example of forming W, the substrate 8 to which the diamond-tungsten composite film 3 is attached is housed in a chemical vapor deposition apparatus, and the inside of the chemical vapor deposition apparatus is heated at a temperature of 250 to 1200.
A film made of W is formed on the surface of the diamond-tungsten composite film 3 by maintaining the temperature at ℃ and introducing the mixed WF ₆ + H ₂ gas into the vapor phase impregnation apparatus. WF ₆
An inert gas such as Ar gas or He gas may be introduced at the same time as + H ₂ gas. In the case of forming a film made of W and C, the gas at the same time methane H _2, WF _6, acetylene,
A gas serving as a carbon source such as benzene is introduced into the reaction furnace. Examples of the compound of tungsten and carbon include WC and W ₂ C. The thickness of the bonding film 5 is preferably about 0.1 to 5 mm in terms of easiness of handling in later steps and strength.

In this way, the composite film 3 and the base material 4 are formed by interposing the bonding film 5 made of at least one of metallic tungsten and tungsten carbide between the diamond-tungsten composite film 3 and the base material 4. The bonding strength of can be further improved as compared with the above embodiment.

According to the present invention, the bonding film 5 may be formed by forming a tungsten carbide film on the composite film 3 side. To form a tungsten carbide film on the composite film 3 side of the bonding film 5, for example, after forming the composite film 3, WF ₆ + H
Gases such as methane, acetylene, and benzene that are carbon sources are introduced into the reaction furnace simultaneously with the _two gases to form a tungsten carbide film, and then WF ₆ + H ₂ gas is introduced into the reaction furnace. By doing so, the bonding film 5
The strength of the multi-layered film including the composite film 3 and the performance is improved, and the adhesion between the composite film 3 and the bonding film 5 is improved.

As shown in FIG. 7, a dense film 7 made of at least one of diamond and diamond-like carbon having a thickness of 0.2 μm or more is formed on the surface of the diamond-tungsten composite film 3 opposite to the base material 4. You may form by. In this case, wear resistance and heat conductivity can be improved. The thickness of the dense film 7 is 2 to 10 μm for improving wear resistance and 10 to 10 for improving thermal conductivity.
About 0 μm is preferable.

In order to confirm the effect of the present invention, the present inventors have made a diamond-tungsten composite film through a bonding film made of W or a compound of W and C, if necessary, a mother film made of cemented carbide. An experiment was conducted to braze the material. And
The brazing yield at the time of joining with the base material was measured, and a cutting test was performed with a tool to which a diamond-tungsten composite film was attached. FIG. 9 shows this tool. In FIG. 9, reference numeral 4 indicates a base material (tool body) made of cemented carbide, to which base the diamond-tungsten composite film 3 of the present invention is brazed by Ag brazing. A bonding film 5 is formed between the composite film 3 and the base material 4, and a dense film 7 made of diamond is formed on the surface of the composite film 3.

The brazing yield test is conducted by heating brazing in argon gas for a short period of time and visually checking the completeness of adhesion of the brazing filler metal in 10 tools and determining the percentage of perfect brazing. Went by.

In the cutting test, five tools were used to cut an aluminum-silicon alloy at a cut of 2 mm, a feed of 0.2 mm, and a cutting speed of 400 mm / min.
The peeling of the composite film after cutting was checked. Table 1 shows the results.

[0055]

[Table 1]

In Table 1, the thickness of part a, the thickness of part b, and c
As shown in FIG. 10, the part thickness means the dense film 7,
It refers to the thickness of the diamond-tungsten composite film 3 and the bonding film 5. In Table 1, the presence or absence of the mesh structure means that
It shows whether or not it has the structure of. The mesh structure may be that shown in FIGS.

According to Table 1, the product of the present invention showed good brazing yield and good peeling after cutting. Sample No. 18 used diamond-like carbon to form the composite film, and other samples used diamond. Sample No. 19 used tungsten carbide to form the composite film, and other samples used tungsten. Further, in the sample No. 20, the bonding film is tungsten carbide, in the samples No. 18 and 21, the bonding film is composed of the W film and the WC film, and the other samples are tungsten. The dense film of sample No. 1 was diamond-like carbon, and diamond was used for the other samples.

Samples No. 23 and 23 are examples in which a diamond film was coated on a substrate made of cemented carbide.

FIG. 11 shows a diagram in which the diamond-tungsten composite film-coated member of the present invention is applied to a die.

[0060]

As described in detail above, according to the present invention, the tungsten and tungsten carbide wraps the diamond-like crystal, the bonding strength between the diamond-like crystal and the tungsten or tungsten carbide is improved, and the composite film itself. It is possible to improve the strength of the composite film and the bonding strength between the composite film and the base material, and it is possible to endure long-term use. Furthermore, by interposing a bonding film made of at least one of metallic tungsten and tungsten carbide between the diamond-tungsten composite film and the base material, it is possible to further improve the bonding strength between the composite film and the base material. .

Further, by forming a dense film made of diamond on the surface of the diamond-tungsten composite film, the characteristics such as abrasion resistance can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a mesh structure in one cross section of a diamond-tungsten composite film of the present invention.

FIG. 2 is a diagram showing a structure forming a part of a mesh structure in one cross section of the diamond-tungsten composite film of the present invention.

FIG. 3 is a diagram showing a structure forming a part of a mesh structure in one cross section of the diamond-tungsten composite film of the present invention.

[Fig. 4] Tungsten metal between diamond crystals,
It is a perspective view showing the state where tungsten carbide is filled.

FIG. 5 is a view showing a member with a diamond-tungsten composite film of the present invention.

FIG. 6 is a view in which a bonding film is formed between a diamond-tungsten composite film-coated member and a base material.

FIG. 7 is a diagram in which a dense film is formed on the surface of a diamond-tungsten composite film.

FIG. 8 is a diagram in which a bonding film is formed between a member with a diamond-tungsten composite film and a base material, and a dense film is formed on the surface of the diamond-tungsten composite film.

FIG. 9 is a perspective view showing a state in which the diamond-tungsten composite film-coated member of the present invention is applied to a tool.

FIG. 10 is an enlarged view showing the vicinity of the diamond-tungsten composite film of FIG.

FIG. 11 is a view in which the diamond-tungsten composite film-coated member of the present invention is applied to a die.

[Explanation of symbols]

 1 ... Diamond Crystal 2 ... Tungsten, Tungsten Carbide 3 ... Diamond-Tungsten Composite Film 4 ... Base Material 5 ... Bonding Film 7 ... Dense Film

Claims (3)

[Claims] 1. A diamond-tungsten filled with at least one of metallic tungsten and tungsten carbide by the CVD method in a void between diamond-like crystals made of at least one of diamond and diamond-like carbon produced by the CVD method. A diamond-tungsten composite film-coated member obtained by brazing a composite film to a base material constituting the member. 2. The diamond-tungsten according to claim 1, wherein a bonding film made of at least one of metallic tungsten and tungsten carbide is interposed between the diamond-tungsten composite film and the base material. A member with a composite membrane. 3. The diamond-tungsten composite film-coated member according to claim 1, wherein a dense film of at least one of diamond and diamond-like carbon is formed on the surface of the diamond-tungsten composite film.