JP2977066B2 - Sliding member - 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 member used for a mechanical part such as an automobile part or a compressor part having a hard coating on a sliding part.
The present invention relates to a sliding member having chromium as a main metal component and further coated with a nitride film made of one or more kinds of other elements.

[0002]

2. Description of the Related Art Sliding parts such as mechanical parts are becoming more and more subject to sliding characteristics such as abrasion resistance and seizure resistance under increasingly severe conditions due to high speed and high output of internal combustion engines and compressors of automobiles. Improvements are expected. Similarly, with respect to cutting tools, it is expected that the sliding characteristics will be improved by increasing the cutting speed. Conventionally, surface treatments such as improvement of abrasion resistance by hard chromium plating, and improvement of seizure resistance by nitridation or molybdenum spraying have been mentioned as measures for improving sliding characteristics.

[0003] However, these methods do not provide sufficient sliding properties as a sliding material, and have recently been relatively chemically modified by physical vapor deposition (PVD) or chemical vapor deposition (CVD). A method for producing a stable Cr—N-based or Ti—N-based hard coating has been studied. However, Cr-
Since the N-based coating has a relatively low coating hardness, the coating is liable to wear. Although attempts have been made to improve this point, sufficient sliding characteristics have not yet been obtained.

[0004] Therefore, the development of a film having higher film hardness and excellent sliding characteristics has been desired, and a Ti-N-based film has attracted attention. However, when a Ti-N based film is used as a sliding member such as a machine part, there is a disadvantage that the film hardness is too high and a mating material is worn out. There is also a drawback that "adaptation" is bad. Here, “initial adaptation” means that the surface of a sliding member having roughness due to machining or film formation itself comes into sliding contact with a counterpart material within a short time after the start of sliding, and the surface is fine and smooth. As a result, the contact surface pressure is reduced by increasing the contact area, making it difficult for the lubricating oil film to break, thereby preventing the occurrence of abrasion and seizure. A sliding member coated with a film having an excessively high film hardness such as a Ti-N-based film has a problem in that abrasion and seizure are likely to occur in the initial stage of sliding due to poor initial adaptation.

[0005]

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a sliding material coated with a film containing Cr as a main metal component, while compensating for the wear resistance of the film and improving the anti-seizure property. An object of the present invention is to solve the above-mentioned problem by coating a hard film having excellent sliding characteristics such as conformability.

[0006]

That is, the sliding member according to the present invention comprises chromium, group M (M; titanium, vanadium, zirconium, niobium, molybdenum, hafnium,
The material is characterized in that the substrate is coated with a film composed of nitrogen (one or two or more metal elements selected from tantalum, tungsten and aluminum). This film has good wear resistance, seizure resistance and initial conformability by adding elements of group M. As a result, the hardness of the film itself is higher than that of the CrN film, and the wear resistance and seizure resistance are improved. Is better than the CrN film. Here, the composition ratio of the metal element of M / (Cr + M) is 1%
If less than 55%, the effect of improving wear resistance is small, while 55%
When the ratio exceeds 1, the seizure resistance and the initial conformability cannot be improved, so that the composition ratio of the metal element is set in the range of 1 to 55%.

Various materials such as Fe-based, Al-based and Ti-based materials can be used as the substrate. The thickness of the Cr-MN-based coating is not particularly limited, but is preferably in the range of 1 to 50 µm. Similarly, the film roughness is preferably 1 μm or less in Ra.

[0008] Further, there is no particular limitation on the partner material,
Cast iron, steel materials, these materials plated with Cr, materials with a thermal spray coating, and the like can be used. Also, the coating of the present invention is formed by PVD or CVD, preferably PVD, on a sufficiently cleaned substrate.

[0009]

[Action] TiN-based coatings have poor initial conformability, while Cr
Since the N film has low abrasion resistance, it tends to cause seizure. However, Cr containing Cr and another metal element M coexist.
By using the -MN-based coating, seizure became difficult to occur. Further, since the wear resistance was improved, the wear after the adaptation was realized was reduced.

Hereinafter, the present invention will be described in detail with reference to examples in which V is selected as the metal element (M).

[0011]

EXAMPLE The substrate for forming a film used in this example is a high chromium steel (JIS standard SUJ-2). The substrate was subjected to ultrasonic cleaning in a CFC solution in advance, and a Cr-V-N-based hard coating was formed on the mirror-finished substrate surface by cathodic arc plasma ion plating according to the procedure described below.

The substrate subjected to ultrasonic cleaning was mounted in a vacuum vessel (chamber) of an ion plating apparatus, and then vacuum was drawn until the pressure in the chamber reached 1.3 × 10 −3 Pa (Pascal). When the degree of vacuum is achieved, the substrate is heated to 300 to 600 ° C. by a heater built in the chamber to release gas components attached or adsorbed on the surface of the substrate.
Cooled down.

When the pressure in the chamber becomes 4 × 10 −3 Pa or less, an arc discharge is generated on the surface of a Cr—V alloy target having various compositions as a cathode, and most of Cr and V are ionized. These elements were ejected from the target surface.

At this time, the jig mounted on the substrate has a
A bias voltage of -1000 V was applied, ionized Cr and V jumping out of the target were attracted to the surface of the substrate and the jig, and these ions were made to collide with the surface to be processed at high speed. An activation treatment of the substrate surface 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.

Thereafter, a small amount of nitrogen gas was introduced into the chamber where the arc discharge occurred, and a portion of ionized Cr and V were combined with the nitrogen gas and deposited as a nitride film on the substrate surface. Thereafter, the nitrogen gas flow rate was further increased to a pressure of about 0.7 to 4.0 Pa, and a bias voltage of 0 to -100 V was applied to the substrate to form a Cr-VN-based hard coating on the substrate surface of 1 to 50 µm. Formed to a thickness of After forming the predetermined film thickness, the temperature in the chamber becomes 150
After cooling to a temperature of not more than ° C, the film-coated substrate was taken out of the chamber. The hardness of the coating is Hv = 1100-
Range of 2200.

Using the coating obtained by the above method, a sliding test was performed.

Example 2 A scuff test was performed using a gray cast iron (FC25) as a mating material using a pin-on-disk 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: Increase from initial 2 MPa to seizure every 1 MPa Friction time: Maintain 180 sec at each load Table 1 shows the scuff test results.

[0018]

[Table 1] No. V / (Cr + V) scuff values present 1 Cr-V-N 15 1.4 shots 2 Cr-V-N 30 1.7 Description 3 Cr-V-N 50 2.0 ratio Cr-N 0 1.0 compare scuff The value is a value when Cr-N to be compared is set to 1.0.

No. 1 according to the present invention. 1, 2 and 3 Cr
-V-N based film is V atom% based on the metal element in the film.
(Hereinafter, simply referred to as “V atom%”) are 15, 3
0 and 50%. C containing no V as a comparative example
A scuff test was performed on the rN-based coating under the same conditions. With respect to the scuff value (baking surface pressure) of 1.0 for the Cr-N coating, In the case of the Cr-VN-based coating of No. 1, the scuff value was improved to 1.4. Further, the scuff value is improved as the V atomic% is increased, and the V-% is 50% Cr-
The VN-based coating showed a scuff value twice as high as that of the Cr-N-based coating.

Example 3 An abrasion test was performed by using a pin-drum type abrasion tester 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 Table 2 shows the wear test results.

[0021]

[Table 2] No. V / (Cr + V) Pin wear amount Drum wear amount 1 Cr-V-N 15 0.9 0.9 Shot 2 Cr-V-N 30 0.8 0.7 Bright 3 Cr-V-N 50 0.6 0.6 ratio Cr-N 0 1.0 1.0 Comparison Pin wear amount and drum wear amount are Ti
The value when -N is set to 1.0.

The Cr-VN-based coating according to the present invention (No.
1, 2 and 3) indicate that V atom% in the coating is 1% each.
5, 30 and 50%. As a comparative example, a wear test was performed on a Cr-N-based coating containing no V under the same conditions. Here, the wear amount of the pin coated with the film was determined from the width of the worn contact surface in the drum rotation direction, and the wear amount of the drum was determined from the wear depth of the drum. Focusing on the amount of pin wear, Cr
Cr-VN-based coatings have a slightly reduced amount of wear compared to -N-based coatings.
It has been reduced to almost half of the system coating. On the other hand, when attention is paid to the amount of wear of the drum, the
In the case of the -VN-based coating, the wear amount is slightly reduced, and in the case of the Cr-V-N-based coating having a V atom% of 50%, the wear amount is suppressed to almost half of the Cr-N-based coating. .

Based on the results of the above scuff test and abrasion test, the Cr-VN-based coating has better seizure resistance, has better initial running-in, and has less wear on the sliding part mating material than the Cr-N-based coating. It was found that the film could be suppressed.

[0024]

As described above, by coating the sliding surface with a nitride film containing Cr as the main metal component and further containing other metal elements, the sliding surface is more mating than the conventional Cr-N-based film. , A sliding member having good initial conformability and excellent sliding characteristics such as abrasion resistance and seizure resistance can be obtained.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C23C 26/00

Claims (1)

(57) [Claims] 1. Chromium, group M (M; titanium, vanadium, zirconium, niobium, molybdenum, hafnium,
Tantalum, one or more metal elements selected from tungsten and aluminum) and nitrogen;
The composition ratio of the metal element is M / (Cr + M) = 1 to 1 in atomic% ratio.
A sliding member comprising a substrate coated with a 55% ion plating film and brought into sliding contact with a counterpart material.