JP2000319784A - Sliding component and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To impart high adhesion to a sliding component by forming a diamondlike carbon film on a carbon ion impregnated layer formed on the surface of a metallic base material by plasma gas contg. carbon and silicon. SOLUTION: A carbon ion impregnated layer 2 is formed on the surface of a metallic base material 1 by ionizing gas contg. carbon, and thereafter, a diamondlike carbon film 3 is formed by using plasma gas contg. carbon and silicon to obtain a sliding component. In the carbon ion impregnated layer 2 formed in this way, the carbon atoms have a concn. distribution in which it is high in the vicinity of the surface and gradually reduces in the depth direction. The diamondlike carbon film 3 is a carbon film from he viewpoint of the chemical compsn., is therefore compositionally and structurally similar to the carbon ion impregnated layer 2 and is thus good in adhesion. Moreover, an Si-C bond is easy to be formed in the film 3 formed in this way, and such Si-C has the action of increasing the adhesion in the surface of the base material by the chemical bonding strength thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding component having a diamond-like carbon film formed thereon and a method of manufacturing the same. More specifically, the present invention relates to a sliding component such as a piston rig, shim, valve lifter, piston, crankshaft, connecting rod, or injection pump plunger for a diesel engine, and a method of manufacturing the same.

[0002]

2. Description of the Related Art The formation of a diamond-like carbon film using a plasma of a gas containing carbon is described in "Structure and Properties of Qusasi-Amorphous" by Weissmantel et al.
Films Prepared by Ion Beam Techniques ", Thin Solid
Films, 72, p19-31 (1980).

[0003] Such a diamond-like carbon film can be formed by various PVD and CVD methods, and is characterized by having a low coefficient of friction with respect to various materials. There is a problem to say.

Japanese Patent Application Laid-Open No. 7-90553 discloses a method of forming a mixed layer at an interface with a base material by ion implantation after forming a hard carbon film or during formation of a hard carbon film to prevent peeling. In this method, a mixed layer of carbon atoms and implanted atoms is formed at the interface between the base material and the hard carbon film by performing ion implantation after or simultaneously with the formation of the hard carbon film. A hard carbon film is formed on a base material having a mixed layer of implanted atoms such as nitrogen and carbon atoms. In addition, the acceleration voltage at the time of ion implantation is 50 ke in consideration of sufficient ion implantation to the inside.
It is said that V or more is good. However, in order to perform ion implantation at such a high accelerating voltage, there is a problem that a special and expensive ion implantation apparatus is required, and it is difficult to perform a large amount of processing due to a small ion beam projection area.

A plasma source ion implantation method using a high voltage pulse (PSII method) is disclosed in US Pat. No. 4,764,
There are 394 and 5,458,927. According to the PSII method, it is disclosed that ions are implanted from all directions by applying a negative high voltage pulse of 20 kV or more to the target, and the surface hardness and wear resistance of the target material are improved. .

However, this PSII method makes it possible to form an ion-implanted layer relatively easily with an inexpensive apparatus. However, since the pulse duty ratio is low, the film formation rate is slow and a film thickness of about 1 micron is required. There is a problem that it takes a long time to obtain.

According to Japanese Patent Application No. 11-57085, the applicant of the present invention improves the adhesion of a diamond-like carbon film made of a gas containing silicon by continuously changing the composition of the mixed component layer in the layer thickness direction. Although a method was proposed, research was conducted on a method for further improving the adhesion.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a sliding component having a diamond-like carbon film having high adhesion, which has been difficult with the prior art, and a method of manufacturing the same.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and comprises a metal base material having a carbon ion implanted layer on the surface, and carbon and silicon on the carbon ion implanted layer. Another object of the present invention is to provide a sliding component comprising a diamond-like carbon film formed from a plasma gas.

In the method for manufacturing a sliding component according to the present invention, a gas containing carbon is ionized on the surface of a metal base material to form a carbon ion-implanted layer, and then diamond is formed using a plasma gas containing a gas containing carbon and silicon. It is characterized in that a like carbon film is formed on a carbon ion implantation layer.

[0011]

[Action] The gas containing carbon is ionized on the surface of the base material,
In the implanted carbon ion implanted layer, the carbon atoms have a high concentration near the surface and a concentration distribution that gradually decreases in the depth direction. Since the diamond-like carbon film is a carbon film in terms of chemical composition, the diamond-like carbon film is similar in composition and structure to the carbon ion implanted layer, and therefore has good adhesion.

Further, a diamond-like carbon film generated from a plasma gas containing silicon and carbon easily forms a Si—C bond in the film. Such Si-C has the effect of increasing the adhesion on the surface of the base material by its chemical bonding force.

Therefore, if a carbon ion implanted layer is previously formed on the surface of the metal base material and a diamond-like carbon film is formed thereon using a plasma gas containing carbon and silicon, the carbon-rich implanted layer can be formed on the carbon-rich implanted layer. Since a diamond-like carbon film in which many Si-C bonds are formed at the interface is formed, the adhesion is improved.

Further, PSI using a gas containing carbon
After forming a carbon ion-implanted layer on the surface of the base material using a negative high-voltage pulse according to the method I, a coefficient of friction is reduced by forming a diamond-like carbon film from a plasma using a gas containing carbon and silicon by an RF plasma CVD method. In addition, a sliding part having good adhesion can be easily manufactured.

As a more preferable method, a method of ionizing a gas containing carbon is a high voltage pulse method, particularly a method using a negative high voltage pulse, which has a peak voltage of 15 kV to 30 kV, a duty ratio of 1% or less, and a rise time of 5 μsec or less. I do. The conventional plasma source ion implantation method requires 2
Although it is disclosed that a negative high voltage pulse of 0 kV or more improves the surface, the method of the present invention uses 15 kV.
The effect can be sufficiently obtained even in the degree. With a waveform with a duty ratio of 1% or less and a rise time of 5 μsec or less, a plasma sheath is generated at a high speed around the substrate, and as a result, high-energy carbon ions are repeatedly implanted at a set frequency onto the substrate surface, so that the implantation is efficient. Layers can be formed.

Although the carbon ion implantation process and the formation of the diamond-like carbon film can be performed by different devices, if two processes are performed in the same device, it is possible to manufacture sliding parts with higher productivity. It is.

As a gas containing carbon and silicon, tetramethylsilane can be used, but tetraethylsilane having a similar structure can also be used.
Furthermore, even if a source gas containing both carbon and an element that easily forms a carbide such as Ti, Cr and W other than silicon is used, a strong bond between Ti and the like and C of the carbon ion implanted layer can be expected.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described more specifically with reference to the drawings.

FIG. 1 is an enlarged view of a part of a sliding component according to the present invention. A carbon ion implanted layer 2 is formed on a surface of a metal base material 1 such as an iron-based material or an aluminum-based material. The carbon ion implanted layer 2 preferably has a maximum carbon concentration (C _max ) of about 10 ¹⁷ / cm ^-3. The carbon ion implanted layer 2 has the highest carbon concentration (C
_max ) is preferably between 250 and 500 °.

A diamond-like carbon film 3 is formed on carbon ion implanted layer 2 using a plasma gas containing carbon and silicon. This thickness is determined by the use of the component and is not particularly limited.

FIG. 2 shows an apparatus used for manufacturing a sliding component according to the present invention, which is used to form a carbon ion-implanted layer by a plasma source ion implantation method. A substrate holder 6 for holding an antenna 5 and a substrate 7 made of a metal base material is provided in a vacuum chamber 4 provided with a vacuum pump 8. At the time of cleaning, RF power of 13.56 MHz is applied to the antenna 5 from the RF power supply 9. The substrate holder 6 has a high-voltage pulse power supply 1
A zero to negative high voltage pulse is applied.

After a gas containing carbon such as hydrocarbons is introduced at a predetermined flow rate from a gas inlet 11 provided in the vacuum chamber to adjust the inside of the vacuum chamber to a predetermined pressure, the substrate 7
When a negative high voltage pulse is applied to the substrate holder 6 holding the substrate, a plasma sheath is formed around the substrate and the substrate holder, and carbon ions in the plasma are accelerated by an electrostatic potential difference generated in the sheath, It collides with the substrate surface with high energy and carbon ions are implanted. Thus, a carbon ion implanted layer is formed on the surface of the base material.

FIG. 3 shows an apparatus used for manufacturing a sliding component according to the present invention.
This is a plasma CVD apparatus, and a diamond-like carbon film 3 is formed on the carbon ion implanted layer 2 by using plasma of a gas containing carbon and silicon such as tetramethylsilane. An upper electrode 15 and a lower electrode 16 are provided in a vacuum chamber 14 having a vacuum pump 12 and a gas inlet 13.
Hz high frequency power is continuously applied. When the upper electrode 15 is grounded and a high-frequency power is applied to the lower electrode 16 under a predetermined pressure determined by a gas containing carbon and silicon introduced at a predetermined flow rate from the gas inlet 13 into the vacuum chamber 14, the upper electrode Plasma is excited between the electrodes. When such an apparatus is used, it takes about one hour on the substrate 7 for one hour.
A diamond-like carbon film having a thickness of about a micron can be formed at a relatively high speed.

Therefore, after a carbon ion implanted layer is formed on the surface of the base material by the PSII apparatus shown in FIG. 2 by the method described above, a diamond-like carbon film is formed by the RF plasma CVD apparatus shown in FIG. Then, various sliding parts can be manufactured.

Hereinafter, specific examples of the present invention will be described together with comparative examples.

Using the apparatus shown in FIG. 2, the base material (SKH5
1) Form a carbon ion implanted layer on the surface. Methane gas was used as the source gas containing carbon. The SKH51 substrate that has been washed in advance is set on the substrate holder 6 in the vacuum chamber 4, and the vacuum pump 8 is evacuated by the vacuum pump 8.

Next, an argon gas is introduced into the vacuum chamber 4, the pressure is adjusted to about 20 mtorr, and high frequency power is applied to the antenna 5 from the RF power supply 9. Thus, argon plasma is generated in the vacuum chamber 4. When a high voltage pulse is applied to the substrate holder 6 from the high voltage pulse power supply in this state, the substrate surface can be cleaned because argon ions collide with the substrate surface with high energy.

Then, methane gas set at a predetermined flow rate is introduced into the vacuum chamber 4 from the gas inlet and the pressure in the chamber is set to about 2 mtorr. In this state, a high voltage pulse is applied to the substrate holder 6 from a high voltage pulse power supply. I do. The condition of the high voltage pulse at this time is that the peak voltage is 15,2.
0,30 kV, repetition frequency 100,500,10
00 Hz. FIG. 4 shows a high voltage pulse waveform at a repetition frequency of 100 Hz and a peak voltage of 20 kV.

After performing a carbon ion implantation process on the surface of the base material, a diamond-like carbon film is formed on the carbon ion implantation layer using the apparatus shown in FIG. Tetramethylsilane was used as a gas containing carbon and silicon.
When tetramethylsilane is used, a diamond-like carbon film containing silicon is formed. Substrate 7 is connected to lower electrode 16
Set on top and vacuum pump 1 by vacuum pump 12
The inside of 4 is exhausted. After evacuating once to a predetermined ultimate vacuum degree, an argon gas is introduced into the vacuum chamber 14 from a gas inlet. In this state, the lower electrode 16 is
When RF power is applied to the substrate 7, argon gas plasma is generated between the upper and lower electrodes to clean the surface of the substrate 7.

After the cleaning process, tetramethylsilane set at a predetermined flow rate is introduced to form a diamond-like carbon film.

The diamond-like carbon film thus formed was evaluated for adhesion by a scratch test and by a friction and wear test (ball-on-disk type, non-lubricated condition). Table 1 summarizes the evaluation results of these tests. For comparison, one prepared by directly forming a diamond-like carbon film on the substrate without performing the carbon ion implantation treatment was prepared. In the scratch test, the critical load value for film peeling was determined in the friction wear test.

[0032]

[Table 1]

From these results, the test material subjected to the carbon ion implantation treatment has a higher critical load value and shows good adhesion as compared with the case where the implantation treatment is not performed.
The influence of the repetition frequency tends to increase the critical load value as the frequency increases at a peak voltage of 15 kV, but no difference is observed at 20, 30 kV.

The coefficient of friction of the film formed in this way is as small as about 0.2 in each case, and is suitable for a sliding part.

[0035]

According to the present invention, as described above, by combining the ion-implanted layer formation and the diamond-like carbon film by the RF plasma CVD method, the adhesion to the base material is improved as compared with the conventional one, A sliding component having a low coefficient of friction can be provided. By using such a sliding part, energy loss due to friction of the sliding part can be reduced. For example, when applied to an automobile engine part, effects such as a reduction in fuel consumption and a reduction in exhaust gas are expected. it can.

According to the method of the present invention, a special ion accelerator is not required in the ion implantation apparatus, so that the apparatus can be constructed at a low cost, and the implantation area can be increased, so that a large amount of processing can be performed. In addition, because there are advantages such as ion implantation into the side surface of the three-dimensional shape,
Manufacture of sliding parts becomes easy.

In addition, since the diamond-like carbon film is formed by applying the RF plasma CVD method,
There is an advantage that the film formation rate is faster than the source ion implantation method.

In this embodiment, the carbon ion implantation process and the formation of the diamond-like carbon film are performed by different devices. However, if two processes are performed in the same device, it is possible to manufacture sliding parts with higher productivity. Is possible.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional view of a sliding component surface showing an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of an ion implantation apparatus for manufacturing a sliding component according to the present invention.

FIG. 3 shows an RF for producing a sliding part according to the invention.
FIG. 2 is a diagram illustrating a schematic configuration of a plasma CVD apparatus.

FIG. 4 is a diagram showing an example of a high-voltage pulse waveform used in an ion implantation apparatus for manufacturing a sliding component according to the present invention.

[Explanation of symbols]

 1. Metal base material 2. 2. Carbon ion implanted layer 3. Diamond-like carbon film Vacuum chamber 5. Antenna 6. Substrate holder 7. Substrate 8. Vacuum pump 9. RF power supply 10. High voltage pulse power supply 11. Gas inlet 12. Vacuum pump 13. Gas inlet 14. Vacuum chamber 15. Upper electrode 16. Lower electrode 17. RF power supply

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C30B 29/04 C30B 29/04 Q 4K044 R F16J 9/26 F16J 9/26 C (72) Inventor Satoshi Tsunoya 4-14-1 Suehiro, Kumagaya-shi, Saitama F-term in Riken Kumagaya Office (reference) 3J044 AA18 BB27 BB35 BB40 CB02 CB40 DA09 DA10 DA14 DA16 4G077 AA03 BA03 DB09 DB16 EE08 TA04 TB05 TB07 TC01 TK02 4K028 BA03 BA21 4K0A A BD04 CA10 EA09 4K030 AA06 BA28 CA02 FA01 JA11 JA17 LA23 4K044 AA01 BA18 BB03 BB17 CA12 CA14

Claims (5)

[Claims] 1. A sliding member comprising: a metal base material having a carbon ion implantation layer on the surface; and a diamond-like carbon film formed on the carbon ion implantation layer by a plasma gas containing carbon and silicon. Moving parts. 2. The method according to claim 1, wherein a gas containing carbon is ionized on the surface of the metal base material to form a carbon ion-implanted layer, and then a diamond-like carbon film is formed using a plasma gas containing carbon and silicon. Manufacturing method of sliding parts. 3. The method for manufacturing a sliding component according to claim 2, wherein the gas containing carbon is methane. 4. The method according to claim 2, wherein the gas containing carbon and silicon is tetramethylsilane. 5. The method of ionizing a gas containing carbon according to a negative high voltage pulse, wherein a peak voltage is 15 kV or more and 30 kV or less, a duty ratio is 1% or less, and a rise time is 5 μsec or less. 5. The method for manufacturing a sliding component according to any one of claims 1 to 4.