JPH06306581A - Film for sliding surface and its formation - Google Patents

Abstract

PURPOSE:To provide the film for a sliding surface which has wear resistance by the matrix of a hard material and exhibits lubricity by the macroparticles of a soft material appearing adequately on the sliding surface. CONSTITUTION:The macroparticles 4 of the soft material are dispersed in the matrix 3 formed of the hard material. Such film 2 for the sliding surface is formed by the method including a stage for forming the matrix 3 of the hard material on the surface of the substrate 1 by a physical vapor deposition method and a stage for sticking the macroparticles 4 of the soft material into the matrix 3 by a vacuum arc vapor deposition method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating for a sliding surface which imparts excellent sliding characteristics to a sliding surface such as a machine part, and a method for forming the same.

[0002]

2. Description of the Related Art A hard coating such as TiN or CrN is formed on the surface of a sliding member in order to meet strict requirements regarding sliding characteristics such as abrasion resistance and seizure resistance for sliding surfaces of machine parts and the like. Is being done. It has been reported in various places that the formation of a hard coating improves wear resistance and seizure resistance, and has already been industrially applied.

Further, there is a method of forming a film having lubricity for the purpose of improving sliding characteristics. This method is a method of forming a lubricating coating made of a solid lubricant such as MoS ₂ , silver, lead or tin, or an alloy or compound based on these metals on the surface of the sliding member. Such a lubricious coating is used for the purpose of improving sliding characteristics in a non-lubricated environment such as vacuum.

[0004]

However, the following problems have been pointed out in both of the above two types of film formation. That is, hard coatings such as TiN and CrN show excellent wear resistance, but on the contrary, due to their high hardness, poor initial conformability, large friction coefficient under non-lubricated conditions, and aggressiveness of mating materials. Height is a problem. Further, a lubricating coating made of silver or the like has a good conformability and exhibits excellent characteristics such as a low friction coefficient, but there is a problem that abrasion resistance is insufficient depending on a friction environment on a sliding surface.

Therefore, there is an increasing demand for a coating film having both the wear resistance of a hard material and the conformability and low coefficient of friction of a soft material. The present invention has been made in view of such a technical background, and an object thereof is to have both advantages of the wear resistance of a hard coating and the conformability and low friction coefficient of a lubricating coating. It is an object of the present invention to provide a coating for a sliding surface that also has the above and a method for forming the coating.

[0006]

In the coating for a sliding surface of the present invention, macro particles of a soft material are dispersed in a matrix formed of a hard material. The method for forming a coating for a sliding surface of the present invention comprises a step of forming a matrix of a hard material on the surface of a substrate by a physical vapor deposition method, and a vacuum arc deposition method in the matrix to form macro particles of a soft material. It is characterized by including a step of attaching.

[0007]

The coating for sliding surfaces of the present invention is provided with wear resistance and seizure resistance by the matrix formed of a hard material. On the other hand, due to the abrasion of the matrix, macro particles dispersed in the matrix appropriately appear on the sliding surface, which exerts lubricity.

Physical vapor deposition creates hard material ions or atoms which deposit on the surface of the substrate to form a matrix of hard material. On the other hand, by the vacuum arc vapor deposition method,
Macro particles, which are molten particles, are by-produced in a certain proportion in the soft material, and these are attached and deposited in the matrix.
Therefore, the coating for the sliding surface of the present invention in which macro particles are dispersed in the matrix of the hard material is formed.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view of a coating 2 for a sliding surface of the present invention formed on a substrate 1. The coating film 2 is formed by non-uniformly dispersing macro particles 4 of a soft material in a matrix 3 of a hard material formed on the substrate 1.

As a hard material for forming the matrix 3, ceramics having excellent wear resistance, specifically III
A nitride of a metal belonging to Group IV, IV or V is preferably used. Of these, TiN and CrN are particularly preferably used. The macro particles 4 have a diameter of 0.1 to 10
It is made of a soft metal material such as silver, tin, and lead having a thickness of about 0 μm. Such macro particles generally correspond to molten particles and the like that are by-produced at a constant rate when the evaporation source is vaporized by the vacuum arc vapor deposition method. As shown in FIG. 1, they may be dispersed non-uniformly, or macro particles 4 having substantially the same shape and size may be contained in the matrix 3 so as to be dispersed uniformly. The dispersion state of the macro particles 4 varies depending on the method of forming the coating film 2, the forming conditions, and the like.

The coating for a sliding surface having such a structure is
Since the matrix 3 that occupies most of the coating surface is made of a hard material having excellent wear resistance, it is excellent in wear resistance, and at the same time, a soft material that is macro particles 4 that gradually appear on the sliding surface due to wear of the matrix 3. Also functions as a lubricant, so it has excellent seizure resistance. Next, a method of forming the sliding surface coating film of the present invention will be described.

FIG. 2 is a schematic diagram of a vacuum arc vapor deposition apparatus for carrying out a method of forming a matrix and macro particles by a vacuum arc vapor deposition method. Vacuum chamber 6
A rotary table 7 on which a substrate 8 is placed is installed below the table. A bias power supply 9 for applying a negative bias voltage to the substrate 8 is connected to the turntable 7. Two vacuum arc evaporation sources 10 and 11, which can be operated independently or simultaneously, are attached above and to the side of the vacuum chamber 6, respectively. Upper evaporation source 10
The target 10 is a soft metal silver as an evaporation material.
a is attached, and the evaporation source 11 on the side is attached with a target 11a made of a hard material such as chromium. Arc sources 12 and 13 are connected to the evaporation sources 10 and 11, respectively.

In the vacuum arc vapor deposition apparatus set as described above, the inside of the vacuum chamber 6 is evacuated from the exhaust port 14 to a vacuum of about 10 ^-4 Torr, and the substrate 8 is moved to 30
Preheated to a temperature of 0 ° C. Next, -80 is applied to the substrate 8.
While applying a bias voltage of 0 V, an arc current of 100 A was passed through the vacuum arc evaporation source 11 to evaporate the chromium target 11a, and the generated chromium ions cleaned the substrate 8 and raised the temperature. After that, the bias voltage applied to the substrate 8 is set to −300 V, and the chromium target 11
The arc current of the evaporation source 11 to which a is attached is set to 200 A, and nitrogen gas (indicated by a black circle in FIG. 2) is introduced into the vacuum chamber 6 from the process gas introduction port 14 to surround the substrate 8. The atmosphere was a nitrogen gas atmosphere of about 10 Torr. Chromium ions generated from the chromium target 11a (shown by white circles in FIG. 2) are combined with nitrogen to form CrN, which is deposited on the substrate 8 to form a matrix that is a hard coating. On the other hand, in parallel with the evaporation of the chromium target 11a, an arc current of 100 A was applied to the evaporation source 10 to which the silver target 10a was attached to evaporate silver. Macro particles having a diameter of 0.1 to 100 μm are by-produced together with silver ions from the silver target 10a, and these are attached to the CrN matrix being formed. In FIG. 2, silver ions and macroparticles are indicated by circles having a lattice.

FIG. 3 shows an enlarged schematic view of the process of forming the film, that is, the surface portion of the substrate 8 during film formation. In FIG. 3, reference numeral 20 denotes a CrN matrix which is being formed, and is formed by combining chromium ions 18 and nitrogen gas 19 which are evaporated from the chromium target 11a. However, silver ions are also released from the silver target 10a,
Although it is contained in the CrN matrix 20 in the form of a solid solution, the content of silver ions is not so large as to significantly change the properties of CrN as a hard material. Further, in the vacuum arc vapor deposition method, chromium macroparticles are by-produced at a constant rate from the chromium target 11a during evaporation, but since the rate is much smaller than silver macroparticles, most of the matrix 20 is made of CrN. Is. on the other hand,
The ratio of macro particles 17 produced as a by-product from the silver target 10a having a lower melting point than that of chromium is high, and the generated macro particles 17 are deposited in the matrix 20 as they are. In the film thus formed, the macro particles 17 are nonuniformly dispersed in the matrix 20 of CrN, as in the film 2 shown in FIG.

The ratio of the macro particles 17 contained in the matrix 20 can be adjusted by the magnitude of the arc current flowing through the silver evaporation source 10 and the Cr evaporation source 11.
Further, in the above embodiment, the vacuum arc vapor deposition method was used as the method for forming the matrix, but the sputtering method,
Other physical vapor deposition methods such as the HCD method may be used. With methods other than the vacuum arc deposition method, all the molecules generated from the target become chromium ions. Since it is necessary to generate macroparticles as a by-product with respect to the silver target, it cannot be substituted by another physical vapor deposition method such as a sputtering method.

Further, although the block-shaped substrate 8 is used in the above embodiment, the present invention is not limited to this, and substrates of various shapes such as pin-shaped and ring-shaped can be used. Furthermore, in the above-mentioned embodiment, CrN and silver were simultaneously deposited on the substrate in parallel, but silver vapor deposition may be performed intermittently, or silver and chromium vapor deposition may be alternately performed. Depending on the pattern, the dispersed state of macro particles in the hard coating can be appropriately changed.

Next, the wear resistance and lubricity of the coating film formed in the above embodiment will be described. In addition, as a comparative example, the measurement results of two kinds of films, that is, a CrN film (Comparative Example 1) and a silver film (Comparative Example 2), which are formed by individually operating a chromium evaporation source and a silver evaporation source, are also combined. Show. In addition, as a reference example, the results obtained by measuring a substrate on which no coating film is formed are also shown. [Abrasion resistance] For the abrasion test, a pin-disk type abrasion tester was used. A pin of high speed steel (SKH51) having a spherical tip was used for the substrate. After forming the coating film of this example and Comparative Examples 1 and 2 on the tip of this pin with a thickness of about 10 μm, the surface was buffed to obtain a sample. The sample prepared in this way was used as engine oil (SEA
10W-30), the amount of wear after sliding for 120 minutes with a cast iron disc under the following conditions was evaluated by the size of the wear mark generated on the surface of the pin. The test results are shown in FIG.

Sliding speed 7 m / min Load 20 kgf Temperature 80 ° C. As can be seen from FIG. 4, the sliding member of the present invention shows excellent wear resistance as the CrN coating of Comparative Example 1. On the other hand, the silver coating of Comparative Example 2 was heavily worn and the substrate was exposed. [Lubricity] Each substrate on the ring and disk (SUS30
No. 4), the coatings of Example and Comparative Examples 1 and 2 having a thickness of 3 μm were formed on the surface. The ring on which the coating was formed and the disk were combined and slid under non-lubricated conditions under the following conditions, and the friction coefficient (μ) was measured 10 minutes after the start of sliding. The measurement result is shown in FIG.

Sliding speed 0.5 m / min Surface pressure 5 kgf / cm ² As can be seen from FIG. 5, the coating of this example has a lower friction coefficient than the CrN coating (Comparative Example 1) and has excellent lubricity. Is shown. In the above embodiment, CrN was used as the hard material forming the matrix and silver was used as the soft material.
The present invention is not limited to this, and other well-known hard materials such as TiN can be used as the hard material, and solid lubricants such as lead can be used as the soft material. Can be created.

[0020]

The coating film for a sliding surface of the present invention has abrasion resistance due to the matrix of a hard material, and exerts lubricity by appropriately displaying macro particles of a soft material on the sliding surface. Therefore, the sliding member on which the coating for a sliding surface of the present invention is formed satisfies both wear resistance and lubricity,
Shows excellent sliding characteristics as mechanical parts.

Further, according to the forming method of the present invention, the sliding surface coating film of the present invention can be easily formed.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a coating for a sliding surface of the present invention.

FIG. 2 is a diagram showing an example of a method for forming a coating for a sliding surface of the present invention.

FIG. 3 is a diagram showing an example of a method for forming a coating for a sliding surface of the present invention.

FIG. 4 is a view showing test results of abrasion resistance of a sliding surface coating of this example, a comparative example, and a reference example.

FIG. 5 is a diagram showing the results of the lubricity test of the sliding surface coating of this example, the comparative example, and the reference example.

[Explanation of symbols]

 1 Substrate 2 Coating 3 Matrix 4 Macroparticles 8 Substrate 10a Silver Target 11a Chrome Target

Claims (2)

[Claims] 1. A coating for a sliding surface, wherein macro particles of a soft material are dispersed in a matrix formed of a hard material. 2. A step of forming a matrix of a hard material on a surface of a substrate by a physical vapor deposition method, and a step of depositing macro particles of a soft material in the matrix by a vacuum arc deposition method. And a method for forming a coating for a sliding surface.