JPH0774429B2 - Sliding material and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding material having a hard coating on a sliding portion of a machine part or the like and a method for producing the sliding material. More specifically, titanium, aluminum, nitrogen and oxygen are used. Ti-Al-N-
The present invention relates to a sliding material coated with an O-based film and a method for manufacturing the sliding material.

[0002]

2. Description of the Related Art In recent years, it has been expected that sliding parts such as mechanical parts will have improved sliding characteristics such as wear resistance and seizure resistance under increasingly severe conditions due to higher rotation speed and higher output of various equipment. There is. As a measure for improving sliding characteristics that has been conventionally performed, surface treatment such as improvement of wear resistance by hard chrome plating and improvement of seizure resistance by nitriding or molybdenum spraying can be mentioned. However, these methods cannot obtain sufficient sliding characteristics as a sliding material, and recently physical vapor deposition (PV
Ti) by the D) method or the chemical vapor deposition (CVD) method.
A method for producing a chemically stable Al-N-based, Cr-N-based, or Ti-N-based hard coating has been studied.

[0003]

This Ti--Al--N type coating has the following many drawbacks when used as a sliding member. A high coating hardness does not pose a problem as a cutting tool, but in the case of a sliding member, it is a drawback that the mating material is worn away. Moreover, the sliding surface of the member coated with the Ti—Al—N-based film is also worn or seized due to the surface of the mating material becoming rough due to wear during sliding. In addition, since the hardness of the coating is too high, the "initial familiarity" with the mating material in contact with the coating is poor. The term "initial familiarity" used here means that the surface of the sliding member that is in sliding contact with the surface of the sliding member wears finely and smoothly within a short time after the start of sliding. To prevent the occurrence of wear and seizure by making it difficult for the lubricating oil film to break. Since the Ti-Al-N-based coating has poor initial familiarity, the Ti-Al-N-based coating is likely to be worn or seized at the initial stage of sliding.

When used under severe sliding conditions,
Although it is not possible to expect improvement in sliding properties unless the adhesion is good, the Ti-Al-N-based coating is
Since the adhesiveness to the substrate is poorer than that of the Cr-N type or Cr-N type coating, a peeling phenomenon occurs during sliding, the contact surface pressure increases remarkably, and it is exposed to a situation where it is very easily seized. It is considered that the reason why the adhesion between the Ti-Al-N-based coating is not good is the difference in the coefficient of thermal expansion between the substrate and the coating.

In addition to such problems in sliding characteristics,
The Ti-Al-N-based coating has the following manufacturing problems. Generally, after coating a hard thin film, it is necessary to smooth the sliding surface of the film by polishing or the like, but if the film hardness is high, smoothing is difficult. Since the hardness of the film of the sliding member coated with the Ti-Al-N-based film is high, it is necessary to perform polishing for a long time using expensive diamond abrasive grains. In addition, polishing for a long time does not result in a uniform finishing allowance, the film thickness becomes non-uniform, and the film is partially lost, resulting in a high rate of defective products.

Therefore, according to the present invention, a coating having good sliding properties such as initial conformability and good adhesion to a substrate is coated,
Moreover, it is an object of the present invention to provide a sliding material and a method for manufacturing the same that solves manufacturing problems.

[0007]

The sliding material according to the present invention comprises titanium, aluminum, nitrogen and oxygen,
Ti-Al with Vickers hardness of 1000-2000
The present invention of a method for producing the same is characterized in that a vapor of titanium and aluminum and a nitrogen gas and an oxygen gas or a gas containing at least nitrogen and oxygen is produced by a PVD method. The coating is applied to the substrate by bringing the substrate into contact with the mixed gas phase.

That is, according to the present invention, by adding oxygen to a Ti-Al-N-based coating used for sliding parts of machine parts or the like, the initial conformability and the adhesiveness with a substrate are enhanced to improve the coating itself. The sliding characteristics are improved, and the hardness is also reduced to reduce the wear of the mating material to prevent seizure and improve the sliding characteristics. The sex is also improved.

It is important that the hardness of the film is within the above range in order to exert such performance. Further, the addition of oxygen is very effective in reducing the wear of the mating material even with a small amount, but in order to obtain a particularly remarkable effect, it is preferably 1 atomic% or more with respect to nitrogen. Also, Ti
The composition of the -Al-N system is not particularly limited, but it may be formed mainly from a substance having a TiN structure in which Al is substituted or solid-dissolved. Next, the thickness of the Ti-Al-NO system coating varies depending on the application of the sliding component, but it is preferably 1 micron or more. Further, as the substrate, iron-based,
A titanium type, an aluminum type, etc. can be used. Hereinafter, changes in physical properties due to addition of O to the Ti-Al-N-based coating will be described.

In the method of the present invention, as the PVD method, ion plating, vapor deposition, sputtering and the like can be used, but ion plating is most preferable. Furthermore, in the PVD method, it is preferable that the volume fraction of oxygen in the gas phase consisting of oxygen and nitrogen is 5 to 30%. If the amount of oxygen is less than this, the expected effect is not obtained, and even if the amount of oxygen is greater, the performance is not particularly improved.

[0011]

Table 1 shows the surface roughness and the film formation rate of the Ti-Al-N-O-based film produced by the method described in the examples. O ₂ / (N ₂ + O ₂ ) in the table indicates the ratio of the flow rate of oxygen gas to the reaction gas flow rate during film formation (hereinafter referred to as oxygen introduction ratio). The surface roughness and the film formation rate were almost the same regardless of the oxygen introduction ratio.

[0012]

[Table 1] No. O ₂ / (N ₂ + O ₂ ) Surface roughness Film thickness Film deposition rate % Ra μm μm μm / min 0 0.40 5.04 0.18 11 0.45 5.32 0.19 20 0.41 5.32 0.19

FIG. 1 shows the X-ray diffraction pattern of these coatings. The iron peak of the high chromium steel used as the substrate
(Sub). It has been reported that a Ti-Al-N-based coating formed by sputtering or ion plating has a structure in which Ti sites in the TiN phase are replaced with Al. Since the peaks detected from these films could all be indexed as TiN peaks, it is considered that Al replaces Ti sites.
Further, as the oxygen introduction ratio increases, (111)
The peak intensity of (200) is higher than
A film having a strong (200) orientation was obtained. Where Ti-
In the Al-N-O based film, while introducing oxygen, T
No peak of the oxide phase of i or Al and Ti-Al is observed, and focusing on the peak of (200), the peak position shifts to the high angle side of 2θ as the oxygen introduction ratio increases. Judging from the above, since the atomic radii of nitrogen and oxygen are relatively close to each other, it is considered that the introduced oxygen is partially substituted by the N site of the Ti (Al) N phase.

FIG. 2 shows the relationship between the oxygen introduction ratio and the film hardness of these films. The Ti-Al-N-O-based coating having an oxygen introduction ratio of 11% had almost the same hardness as the Ti-Al-N-based coating in which oxygen was not introduced. Further, in the Ti-Al-N-O-based coating in which the oxygen introduction ratio was 20%, a rapid decrease in coating hardness was observed. Therefore, Ti (A
1) It is clear that the hardness of the N phase is reduced at the N site with partial substitution. Hereinafter, the properties of the sliding material of the present invention will be described in more detail with reference to examples.

[0015]

EXAMPLE The film-forming substrate used in this example is high chromium steel (JIS standard SUJ-2). The mirror-finished substrate is subjected to ultrasonic cleaning in a flon solution and sufficiently degreased, and then coated with a Ti-Al-NO hard coating by a cathodic arc plasma type ion plating method according to the procedure described below. did.

The ultrasonically cleaned substrate was placed in a vacuum container (chamber) of an ion plating apparatus, and the chamber was evacuated to a pressure of 1.3 × 10 ⁻³ Pa (pascal). . From the time when this degree of vacuum is achieved, the substrate is heated to 300 to 600 ° C. by the heater built in the chamber to release the gas components adhering to or adsorbing to the substrate surface, and then to 200 ° C. Cooled. When the chamber internal pressure became 4 × 10 ⁻³ Pa or less, arc discharge was generated on the surface of the Ti-50 at% Al target used as the cathode, and most of Ti and Al were ionized and blown off from the target surface. I let it out.

At this time, the substrate is -700 to -1000V.
Was applied to the target, the ionized Ti and Al ejected from the target were attracted to the surface of the substrate, and these ions were made to collide with the surface to be treated at high speed. The surface activation treatment was performed by so-called sputter cleaning in which oxides and the like on the surface to be treated were scraped by the collision of the ionized metal. Further, when a small amount of nitrogen gas is introduced into the chamber simultaneously with the occurrence of arc discharge, a part of ionized Ti and Al is combined with the nitrogen gas and deposited as a Ti-Al-N-based film on the surface of the substrate. .

After that, the flow rate of nitrogen gas is further increased, and a predetermined amount of oxygen gas is introduced so that the pressure is about 1.3 Pa.
A bias voltage of 20 to -100 V was applied to form a Ti-Al-NO based hard coating on the surface of the substrate. After forming a predetermined film thickness, the temperature inside the chamber was cooled to 150 ° C. or lower, and then the substrate coated with the film was taken out of the chamber. For comparison, a Ti—Al—N-based film that does not introduce oxygen, which has been conventionally used, was also prepared.

FIG. 3 shows the relationship between the oxygen loading ratio and the critical load value (Newton unit) obtained by the scratch test, which is one of the methods for evaluating the adhesion between the coating and the substrate. Ti-
Ti-Al-N- with oxygen introduced into the Al-N-based film
It was found that in the O-based coating, the Lc value was increased and the adhesion between the substrate and the coating was improved.

A scuff test was conducted on these films with a gray cast iron (FC25) as a mating member using a pin-on-disc type friction tester. The scuff test conditions were as follows. Lubrication method: Motor oil # 30, oil temperature 80 ° C, oil amount 4
cc / sec Friction speed: 8 m / sec Contact load: Increased from 2 MPa in the initial stage in steps of 1 MPa,
Friction time until baking: Holds for 180 seconds at each load

The results obtained by the above method are shown in FIG. 18M for Ti-Al-N based film that does not introduce oxygen
The scuff value was about Pa, but the oxygen introduction ratio was 20%.
The Ti-Al-N-O-based coating of No. 2 showed a scuff value of 32 MPa, and it was found that the seizure resistance was improved by introducing oxygen.

Further, by the pin-drum type abrasion tester,
Abrasion test was performed using gray cast iron (FC25) for the drum. The wear test conditions were as follows. Lubrication method: Motor oil # 30, oil temperature 80 ° C, oil amount 8
cc / sec Drum rotation speed: 5 m / sec Contact load: 1.5 MPa Test time: 30 ksec

The amount of wear of the pin coated with the coating and the amount of wear of the drum are shown together in FIG. Here, the wear amount of the pin was obtained from the width of the worn contact surface in the drum rotation direction, and the wear amount of the drum was obtained from the wear depth of the drum. Focusing on the amount of wear of the pin, Ti-Al-N-O is applied to the Ti-Al-N-based coating.
The amount of wear of the system coating was almost the same. On the other hand, focusing on the amount of wear of the drum, the amount of wear decreased as the oxygen introduction ratio increased.

From the results of the above scuffing test and wear test, Ti-introduced oxygen into the Ti-Al-N-based coating was used.
The Al-N-O-based coating has the same level of wear resistance, but has a low coating hardness, which suppresses the wear of the mating material of the sliding portion and at the same time has good initial familiarity and excellent seizure resistance. It was found to be a film. Further, it is considered that the introduction of oxygen improves the adhesion to the substrate and makes it difficult for the peeling phenomenon to occur, which improves the seizure resistance.

[0025]

As described above, Ti-A is applied to the sliding surface.
By coating with an I-N-O based film, the conventional Ti-
Adhesion to the substrate is better than in the Al-N-O type coating, initial conformability is good, the mating material does not wear, and the sliding characteristics are excellent in wear resistance and seizure resistance. An excellent sliding material can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing an X-ray diffraction pattern of a Ti—Al—N—O-based film produced by cathodic arc plasma type ion plating.

FIG. 2 is a diagram showing the relationship between the oxygen introduction ratio and the film hardness of a Ti—Al—N—O system film produced by cathodic arc plasma type ion plating.

FIG. 3 is a diagram showing a relationship between an oxygen introduction ratio and a scratch critical load value of a Ti—Al—N—O based film produced by cathodic arc plasma type ion plating.

FIG. 4 is a diagram showing a result of a scuff test.

FIG. 5 is a diagram showing a result of a wear test.

Claims (3)

[Claims] 1. Ti-A mainly composed of a TiN-structured material composed of titanium, aluminum, nitrogen and oxygen and having a Vickers hardness of 1000 to 2000.
A sliding material having a substrate coated with an l-N-O film. 2. The coating is applied to the substrate by contacting the substrate with a vapor phase of titanium and aluminum vapor and a mixture of nitrogen gas and oxygen gas or a gas containing at least nitrogen and oxygen by the PVD method. The method for producing a sliding material according to claim 1. 3. The method for producing a sliding material according to claim 2, wherein the volume fraction of oxygen in the mixed gas phase is 5 to 30%.