JP2002266697A - Slide member and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a slide member excellent in wear resistance which can be expected to have sufficient durability even under a sever condition in the application of fuel direct injection, EGR(exhaust gas recirculation), or the like for reducing the CO2 and NOx in exhaust gas of an engine for automobile or the like and improving the fuel consumption. SOLUTION: This slide member comprises a film formed of a mixed composition of a crystal phase of metal nitride, metal carbide or metal carbonitride and an amorphous phase applied on a base material. The slide member is manufactured by bringing the base material into contact with a metal vapor or reaction gas by PVD method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine for various industrial machines and transportation equipment, a sliding member for an automobile engine, particularly a cam shim shim (cam follower), and a piston ring.

[0002]

2. Description of the Related Art Piston rings used in reciprocating internal combustion engines are required to have high wear resistance. Therefore, for the purpose of imparting wear resistance to the piston ring,
A piston ring having a hard chromium plating layer formed on a sliding surface has been frequently used as a piston ring for an internal combustion engine. By the way, in recent years, internal combustion engines have become increasingly faster,
There is a trend to increase the output, and therefore, the operating conditions of the piston ring are becoming increasingly severe. Therefore, for example, in Japanese Patent Application Laid-Open No. 7-286261, CrN
And a coating comprising a mixture of Cr2N and V2, and the coating has a Vickers hardness of about Hv 1700.

[0003] On the other hand, for cams and shims which are valve mechanisms of internal combustion engines, alloy cast iron is generally used for cams and carburized and quenched material of alloy steel is used for shims. An example in which a shim is coated with a high-hardness thin film in order to reduce the surface roughness is disclosed in JP-A-5-163909. This is to reduce the frictional resistance by mirror-finishing the cam surface on the mating side with a high-hardness film formed on the shim. It is described that TiN is suitable as the high hardness thin film (see Examples).

As described above, in order to improve the wear resistance of the piston ring and the shim, a CrN coating and the like for the piston ring and a TiN coating and the like for the shim have been studied in addition to the chromium plating.

[0005]

However, these coatings are important from the viewpoints of environmental protection and energy saving, and include direct fuel injection or EGR (exhaust gas recycle) for reducing CO ₂ and NO _x in automobile exhaust gas and improving fuel efficiency. Sufficient durability could not be expected under severe conditions when (circulation) was applied. Therefore, the present invention is based on a coating that can provide a longer life than conventional engines even under severe wear conditions such as direct fuel injection or EGR (exhaust gas recirculation) for reducing CO ₂ and NO _x in automobile exhaust gas and improving fuel efficiency. To obtain a highly durable sliding member. In addition, severe conditions are similarly required for internal combustion engines other than automobiles, and the object is to obtain a highly durable sliding member.

[0006]

According to the present invention, there is firstly provided a coating film comprising a mixed structure of a crystalline phase and an amorphous phase comprising a metal nitride or a metal carbide or a metal carbonitride on a substrate. 2. The sliding member according to claim 1, wherein the coating has a crystalline phase ratio of 5% to 95%, and the remainder is an amorphous phase. 3. 3 is a sliding member, wherein the grain size of the crystal phase is 1 nm to 100 nm in the sliding member, and 4th is a coating having a Knoop hardness of 2,000 to 8,000 in the sliding member. Fifth, in the above-mentioned sliding member, a nitride, a carbide or a carbonitride of an element belonging to Group IVa, Va, VIa of the Periodic Table such as Ti, Cr, Nitride or carbide of group IIIb or IVb element of Si periodic table as amorphous phase Or a cam ring, a cam follower and a cam shim that use the above-mentioned sliding member. Eighth aspect of the present invention is to provide a method of manufacturing a sliding member according to the eighth aspect, wherein the coating is formed by bringing a substrate into contact with a metal vapor or a reactive gas by a PVD method. Solve the problem.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a film composed of a mixed structure of a crystalline phase and an amorphous phase composed of a metal nitride or a metal carbide or a metal carbonitride, the movement of dislocations which is important in the destruction of the film is caused within the crystalline phase. Occur. Even if the dislocations move to the grain boundaries, the dislocations are stopped there because the grain boundaries are in an amorphous phase. Therefore, the hardness (strength) increases. Other important factors related to fracture include crack generation. However, in the present invention, crack generation is considered to occur in an amorphous phase, and the size is limited by crystal grain boundaries. In this way, a coating having high hardness (high strength) is obtained, and a sliding member formed by coating this coating on a base material can solve the above-mentioned problem. Preferably, in a film having a mixed structure of a crystalline phase and an amorphous phase, the above problem can be solved by forming a film in which the proportion of the crystalline phase is 5% to 95% and the remainder is an amorphous phase. If the crystal phase is less than 5%, the amount of the amorphous phase is too large, the crack becomes too large, and the hardness is lowered.
On the other hand, if the crystal phase is larger than 95%, plastic deformation of the crystal phase easily occurs, and sufficient hardness (strength) cannot be obtained. The ratio of the crystal phase is more preferably 10% to 70%.

[0008] More preferably, the grain size of the crystal phase is from 1 nm to
By limiting the size to 100 nm, the generation of dislocations in the crystal grains can be suppressed as much as possible, and the above problem can be solved by increasing the hardness due to the refinement of the crystal grains. If the crystal grain size is less than 1 nm, the crystal grain boundaries become longer and cracks are more likely to enter,
On the contrary, the hardness does not improve. Further, the crystal grain size is 100 n.
If it is larger than m, the crystal phase is likely to be plastically deformed, and sufficient hardness (strength) cannot be obtained. A more preferable range of the crystal grain size is 1 to 10 nm.

It is more preferable to define Knoop hardness. Preferably, the hardness of the coating is limited to a Knoop hardness of 2000 to 8000, so that the sliding member becomes more effective. More preferably Knoop hardness 300
0 to 8000.

In realizing the above, preferably, the crystalline phase is a nitride, carbide or carbonitride of an element belonging to Group IVa, Va, VIa of the periodic table of Ti, Cr, etc. A nitride, carbide, or carbonitride of a Group IVb element in the Table.

It is more effective to select a nitride, carbide or carbonitride of Cr as the crystal phase and a nitride, carbide or carbonitride of Si as the amorphous phase.

When these coatings are applied to a sliding member for an automobile engine, particularly to a shim of a piston ring or a cam shim, the effect is remarkably exhibited.

Regarding the method of producing these coatings, PVD
Metal nitride or metal carbide which is a crystalline phase in the vapor deposition process of metal vapor mixed with metal chromium or metal titanium or silicon, preferably in a reduced pressure nitrogen gas atmosphere or a hydrocarbon gas atmosphere such as methane. It can be formed by forming a mixed structure of a metal carbonitride, a metal nitride which is an amorphous phase, a metal carbide or a metal carbonitride.

Examples of the present invention will be described below, but the present invention is not limited to them.

[0015]

Example 1 A nitride of Cr and a nitride of Si were selected as metal nitrides, and a mixed metal of Cr-Si was used to form a film by an ion plating method, which is a kind of PVD method. Specifically, Cr
A target in which Si and Si were mixed was prepared, and a film was formed under the following conditions by an arc ion plating method.

Arc current: 150 A Bias voltage: 100 V N ₂ Pressure: 2.66 Pa

As a result, it was possible to obtain a composite film in which the nitride of Cr was a crystalline phase and the nitride of Si was an amorphous phase. This coating was applied to a disk made of stainless steel or a disk made of chromium molybdenum steel, which was a disk test piece of a ball-on-disk test, for about 3 minutes.
Coating was performed with a thickness of μm, and a ball-on-disk friction and wear test was performed using alumina balls (see FIG. 1). Table 1 shows the friction and wear test conditions.

[0018]

[Table 1]

As a comparative material, a chromium plating material, a TiN coating material, a CrN coating material, and a chromium molybdenum steel having no coating were prepared. A chrome plating was set to 100 for a test for a piston ring, and a chromium molybdenum steel was set for a test for a shim. The results are shown in Tables 2 and 3, respectively, assuming 100.

[0020]

[Table 2]

[0021]

[Table 3]

It can be seen that the wear amount of TiN and CrN is reduced to less than 1/2 compared to chromium plating. For it,
It can be seen that the wear amount of the product of the present invention is further reduced to 1/5 or less of chromium plating and chromium molybdenum steel. It is said that the severe conditions when direct fuel injection and EGR (exhaust gas recirculation) are applied are those that are five times more severe than the current conditions of chromium plating and chromium molybdenum steel. The relative wear amounts were 10 and 17, respectively, and it was found that this example satisfied the conditions.

X-ray diffraction of the coating of the product of the present invention was performed. The results are shown in FIG. Peak of CrN was observed only peaks the Si ₃ N ₄ was not observed, believed to be composite coating of an amorphous phase of the crystalline phase and Si-N of CrN. This was confirmed by observation with a transmission electron microscope, and a lattice image was observed for CrN, but no lattice image was observed for the nitrided portion of Si.

Further, the mixing ratio of Cr and Si of the target was appropriately changed, and the ratio of the crystalline phase and the amorphous phase was changed. Table 4 shows the relationship between the ratio of the crystal phase and the relative wear at that time.
As a result, when the proportion of the crystal phase is 3%, the relative wear amount is as large as 30 or more, which is a problem to be solved by the present invention, which is important from the viewpoint of environmental protection and energy saving. _2, direct fuel injection and EGR (exhaust gas recirculation) for of the nO _x reduction and fuel efficiency is improved can not be expected sufficiently durable under severe conditions when applied. Further, when the crystal phase is increased to 6%, the relative wear amount becomes 18 or less,
Durability under the above severe conditions is obtained. On the other hand, when the proportion of the crystal phase is 94%, the relative wear amount is 17, and the durability under the above severe conditions can be obtained. However, when the proportion of the crystal phase is further increased to 98%, the relative wear amount becomes 50%. Above
The durability deteriorates. As described in the relationship between the ratio of the crystal phase / amorphous phase and the hardness (strength) of the coating film, when the ratio of the crystal phase / amorphous phase becomes appropriate, the endurance under the above-mentioned severe conditions is obtained. Therefore, the ratio of the crystal phase is set to 5% to 95% from the viewpoint of obtaining the property.

[0025]

[Table 4]

When the ratio of the crystal phase was examined more finely, as shown in Table 4, when the ratio of the crystal phase was 9%, the relative wear amount was 17, but when the ratio of the crystal phase was 12%, the relative wear amount was 17. The amount will be 11 or less. Further, the ratio of the crystal phase is 6
When it is 5%, the relative wear amount is as low as 10, but when the ratio of the crystal phase is 72%, the relative wear amount is 16 or more. From this, it is more preferable that the ratio of the crystal phase is 10% to 70%.
And

Next, the film forming conditions were appropriately changed, and the particle size of the crystal phase of the film was changed. Table 5 shows the relationship between the crystal grain size and the relative wear at that time. As a result, when the crystal grain size is 0.6 nm, the relative wear amount is as large as 30 or more, and sufficient durability cannot be expected under the above severe conditions. Increase the crystal grain size, 1.5
If it is set to nm, the relative wear amount will be 11 or less, and the durability will be sufficient even under the above severe conditions. On the other hand, by increasing the crystal grain size,
At 95 nm, the relative wear amount is 19 or less, and the durability is sufficient even under the above severe conditions.
In this case, the relative wear amount becomes 50 or more, and the durability becomes insufficient. As a result, the preferred range of the crystal grain size was 1 nm to 100 nm.

The crystal grain size was examined more finely. As shown in Table 5, when the crystal grain size was 8 nm, the relative wear amount was 1
Although it is 1 or less, the relative wear amount becomes 17 or more when the crystal grain size is 12 nm. For this reason, the crystal grain size is more preferably set to 1 nm to 10 nm.

[0029]

[Table 5]

Further, the Knoop hardness of the film was changed by changing the film forming conditions and the like. Table 6 shows the relationship between the Knoop hardness of the coating and the relative wear at that time. As a result, the Knoop hardness of the coating is 1
In the case of 600, the relative wear amount is as large as 40, and the durability is insufficient under the above severe conditions. Further increase the hardness 2500
In this case, the relative wear amount is reduced to 17, and sufficient durability can be obtained even under the above severe conditions. On the other hand, the hardness was further increased,
If it is set to 500, the relative wear amount becomes 12 or less, and the durability is maintained even under the above-mentioned severe conditions.
If it is set to 00, it becomes brittle as described above, and the relative abrasion increases instead to 40 or more, and the durability is not sufficient under the above severe conditions. As a result, the preferable range of the Knoop hardness was 2,000 to 8,000.

[0031]

[Table 6]

When the hardness was examined in more detail, as shown in Table 6, when the Knoop hardness was 3500, the relative wear amount was 13 or less. For this reason, the more preferable range of the Knoop hardness is 3000 to 8000.

[0033]

Example 2 Ti nitride and Si nitride were selected as metal nitrides, and a film was formed by an ion plating method which is a kind of PVD method. As a result, a composite film in which the nitride of Ti was in the crystalline phase and the nitride of Si was in the amorphous phase was obtained. This film was coated on a stainless steel disk or a chromium molybdenum steel disk as a disk test piece of a ball-on-disk test in a thickness of about 3 μm in the same manner as in Example 1, and a ball-on-disk friction and wear test was performed using an alumina ball. (See FIG. 1). Table 1 shows the friction and wear test conditions. Table 2 shows the results of the wear test in which chromium plating is expressed as 100, and Table 3 shows the results of the wear test in which chromium molybdenum steel is expressed as 100.

It can be seen that the wear amount of the product of the present invention is 1/5 or less of the chromium plating and chromium molybdenum steel. The most severe conditions when direct fuel injection or EGR (exhaust gas recirculation) are applied
It is said that the conditions are more than twice as severe, so in this friction test, the relative wear amount was 12, 10, respectively.
This example was found to satisfy the conditions.

[0035]

Embodiment 3 As metal carbonitrides, Ti carbonitride and Si
And a film was formed by an ion plating method, which is a kind of PVD method. As a result, a composite coating having a crystalline phase of TiCN and an amorphous phase of Si nitride was obtained. This film was subjected to a friction test under the same conditions and conditions as in Example 1.
The results are shown in Tables 2 and 3. In this embodiment, the relative wear amounts are 15 and 12, respectively.
The abrasion resistance was more than doubled and it was found that the condition was satisfied.

[0036]

Embodiment 4 As metal carbonitrides, Cr carbonitrides and Si
Was selected, and a CrSiCN film was formed by an ion plating method, which is a kind of PVD method. As a result, a composite film having a crystalline phase of CrCN and an amorphous phase of Si nitride was obtained. This film was subjected to a friction test under the same conditions and conditions as in Example 1. The results are shown in Tables 2 and 3. In this example, the relative abrasion amounts were 11 and 12, respectively. This example shows that the abrasion resistance is 5 times or more of the present condition and satisfies the conditions.

[0037]

According to the present invention, conventional chromium plating, TiN
The conventional engine is not suitable for severe wear conditions when direct fuel injection or EGR (exhaust gas recirculation) is applied to reduce CO ₂ and NO _x in automobile exhaust gas, where the durability is insufficient with CO2 or CrN coating. It is possible to obtain a film having the above life.

[Brief description of the drawings]

FIG. 1 is a view showing a friction and wear test method.

FIG. 2 is a diagram showing a comparison between X-ray diffraction results of an embodiment of the present invention and a conventional CrN coating.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F01L 1/16 F01L 1/16 F16J 9/26 F16J 9/26 C (72) Inventor Nie Asane, Osaka 2-8-1, Tsuda Yamate, Hirakata City, Japan Ion Engineering Laboratory Co., Ltd. (72) Inventor Shinya Iwamoto 2-8-1, Tsuda Yamate, Hirakata City, Osaka Prefecture F-Term, Ion Engineering Laboratory Co., Ltd. 3G016 BB02 BB05 EA00 EA24 FA21 GA02 3J044 AA02 BA01 BB06 BB20 BB28 BB30 BB35 BB36 BC06 DA09 4K029 AA02 BA54 BA55 BA56 BA57 BA58 BA60 BB08 BB10 BC02 BD04 CA04 DD06

Claims (8)

[Claims] 1. A sliding member comprising a base material coated with a coating made of a mixed structure of a crystalline phase and an amorphous phase made of a metal nitride, a metal carbide, or a metal carbonitride. 2. The coating according to claim 1, wherein the proportion of the crystalline phase is 5% to 95%.
The sliding member according to claim 1, wherein the remainder is an amorphous phase. 3. The particle size of the crystal phase of the coating is from 1 nm to 100 n.
The sliding member according to claim 1, wherein the size of the sliding member is m. 4. The coating has a Knoop hardness of 2000 to 800.
4. Hardness up to 0.
The sliding member according to any one of the above. 5. The film of the coating is composed of Ti, Cr, etc.
2. A nitride, carbide or carbonitride of an element belonging to group a, VIa, and the amorphous phase is a nitride, carbide or carbonitride of an element belonging to group IIIb or IVb of the Si periodic table. 5. The sliding member according to any one of claims 4 to 4. 6. A piston ring using the sliding member according to claim 1. 7. A shim of a cam shim using the sliding member according to claim 1. 8. The sliding member according to claim 1, wherein the coating is formed by metal vapor deposition by PVD.
A method for producing a sliding member, wherein the sliding member is formed by contacting a reaction gas with a substrate.