JPH06330347A - Sliding member - Google Patents

Abstract

PURPOSE:To provide a sliding member excellent in wear and seizing resistance by forming the coating film of a sliding member with metallic elements such as Ti and Cr and N and specifying the compsn. ratio between the metallic elements. CONSTITUTION:A coating film is formed with Ti, M (M is one or more kinds of metallic elements selected from among Cr, V, Zr, Nb, Mo, Hf, Ta, W and Al) and N. The compsn. ratio between the metallic elements is allowed to satisfy M/(Ti+M)=1-45 atomic %. A substrate is coated with this coating film to obtain the objective sliding member having satisfactory initial fitness and excellent in sliding characteristics.

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 machine 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 titanium as a main metal component and a nitride film made of one or more metal elements.

[0002]

2. Description of the Related Art Sliding parts such as mechanical parts are subject to sliding characteristics such as wear resistance and seizure resistance under increasingly severe conditions due to higher rotation speed and higher output of internal combustion engines and compressors of automobiles. It is expected to improve. Similarly, in cutting tools, it is expected that the sliding characteristics will be improved by increasing the cutting speed. Conventionally, as a measure for improving sliding characteristics, 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 do not provide sufficient sliding properties as a sliding material, and have recently been relatively chemically chemically prepared by physical vapor deposition (PVD) or chemical vapor deposition (CVD). Methods for producing stable Cr-N-based and Ti-N-based hard coatings have been investigated. However, Cr-
Since the N-based coating has a relatively low coating hardness, the coating is likely to wear, and although attempts have been made to improve this point, sufficient sliding characteristics have not yet been obtained.

Therefore, it is desired to develop a film having higher film hardness and excellent sliding characteristics, and a Ti-N-based film has attracted attention. However, the Ti-N-based coating has a drawback that the hardness of the coating is too high when it is used as a sliding member such as a machine part, and it causes abrasion of the mating material. "Familiarity" also has the disadvantage. Here, "initial familiarity" means that the surface of the sliding member, which has roughness caused by machining or film formation itself, comes into sliding contact with the mating material within a short time after the start of sliding, and the surface is minute and smooth. As a result of abrasion, the contact surface pressure is reduced by increasing the contact area, making it difficult for lubricant oil film breakage to occur, thereby preventing wear and seizure. A sliding member coated with a film having a too high film hardness such as a Ti-N-based film has a problem that it is likely to cause abrasion or seizure at the initial sliding stage due to poor initial fitting.

[0005]

In view of the above points, the present invention provides a sliding material coated with a film containing Ti as a main metal component, which has excellent sliding characteristics such as wear resistance and seizure resistance. The object of the present invention is to solve the above problems by coating a hard film having good initial familiarity.

[0006]

[Means for Solving the Problems] That is, the sliding member according to the present invention is made of titanium, an M group (M; chromium, vanadium, zirconium, niobium, molybdenum, hafnium,
It is characterized by being a material in which a substrate is coated with a film composed of one or more kinds of metal elements selected from tantalum, tungsten and aluminum) and nitrogen. This coating has improved wear resistance, seizure resistance, and initial running-in property than the TiN coating, even though the hardness of the coating itself is lower than that of the TiN coating by adding the elements of group M. Is. Here, when the metal element composition ratio of M / (Ti + M) is less than 1%, the effect of improving the initial running-in is small, and when it exceeds 45%, the seizure resistance cannot be improved, so that the metal element composition ratio is 1%. The range was up to 45%.

As the base material, various materials such as Fe-based material, Al-based material and Ti-based material can be used. The thickness of the Ti-M-N-based coating is not particularly limited, but is preferably in the range of 1 to 50 μm. Similarly, the film roughness Ra is preferably 1 μm or less.

Further, the mating material is not particularly limited, and cast iron or steel material, these materials plated with Cr, materials having a thermal spray coating, etc. can be used. Further, the coating film of the present invention is formed by PVD or CVD, preferably PVD, on a sufficiently cleaned substrate.

[0009]

[Function] The TiN-based coating has poor initial conformability, while Cr
Since the N film has low wear resistance, it easily causes seizure, but Ti containing Ti and another metal element M coexists.
By using the -MN type coating, it became difficult for seizure to occur. In addition, since the initial familiarity was good, the wear after the familiarization 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).

[0010]

EXAMPLE The film-forming substrate used in this example is high chromium steel (JIS standard SUJ-2). The substrate was previously subjected to ultrasonic cleaning in a flon solution, and a Ti-VN hard coating was formed on the mirror-finished substrate surface by cathode arc plasma ion plating according to the procedure described below.

The ultrasonically cleaned substrate was mounted in a vacuum container (chamber) of an ion plating apparatus, and then vacuumed until the pressure in the chamber reached 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 on the substrate surface, and then 200 ° C.
Cooled down.

When the pressure in the chamber becomes 4 × 10 -3 Pa or less, arc discharge is generated on the surface of the Ti-V alloy target having various compositions used as the cathode, and most of Ti and V are ionized. It was ejected from the target surface.

At this time, the jig on which the base body is mounted is -700 to
A bias voltage of -1000 V was applied, ionized Ti and V jumping from the target were attracted to the surfaces of the substrate and jig, and these ions were made to collide with the surface to be processed at high speed. The 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.

After that, a small amount of nitrogen gas was introduced into the chamber where the arc discharge occurred, and a part of ionized Ti and V were combined with the nitrogen gas and deposited as a nitride film on the surface of the substrate. Thereafter, the flow rate of nitrogen gas is further increased to a pressure of about 0.7 to 4.0 Pa, and a bias voltage of 0 to -100 V is applied to the substrate to form a Ti-VN hard coating on the substrate surface of 1 to 50 μm. Was formed to a thickness of. After forming a predetermined film thickness, the chamber temperature is 150
After cooling to below ℃, the film-coated substrate was taken out of the chamber. The hardness of the film is Hv = 1500
It was in the range of 2500.

A sliding test was carried out using the film obtained by the above method. Example 2 A scuff test was carried out by a pin-on-disc type friction tester using gray cast iron (FC25) as a counterpart material. 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: Initially increased from 2 MPa to seizure every 1 MPa. Friction time: Hold for 180 seconds under each load Table 1 shows the results of the scuff test.

[0016]

[Table 1] No. V / (Ti + V) scuff values present 1 Ti-V-N 13 1.2 rounds 2 Ti-V-N 28 1.6 Description 3 Ti-V-N 45 1.8 ratio Ti-N 0 1.0 compare scuff The value is a value when Ti-N to be compared is set to 1.0.

No. 1 according to the present invention. 1, 2 and 3 Ti
-V-N system coating is V atom% to the metal element in the coating.
(Hereinafter, simply referred to as “V atom%”) is 13, 2 respectively
8 and 45%. As a comparative example, T containing no V
A scuffing test was performed on the iN coating under the same conditions. For the scuff value (baking surface pressure) of the Ti-N-based coating of 1.0, No. In the Ti-VN coating of No. 1, the scuff value was improved to 1.2. Further, as the V atom% is increased, the scuff value is improved, and the V atom% is 45% Ti-.
The VN-based coating showed a scuff value almost twice that of the Ti-N-based coating.

Example 3 A pin-drum type abrasion tester was used to perform an abrasion test 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.

[0019]

[Table 2] No. V / (Ti + V) Pin wear amount Drum wear amount Main 1 Ti-V-N 13 0.8 0.9 Shot 2 Ti-V-N 28 0.9 0.7 Bright 3 Ti-V-N 45 0.9 0.6 ratio Ti-N 0 1.0 1.0 compare pin wear amount and drum wear amount is compared Ti
It is a value when -N is set to 1.0.

The Ti-VN coating according to the present invention (No.
1, 2 and 3) have a V atomic% of 1 in the coating, respectively.
3, 28 and 45%. As a comparative example, a wear test was conducted under the same conditions for a Ti-N-based coating containing no V. Here, the amount of wear of the pin coated with the film was obtained from the width of the worn contact surface in the drum rotation direction, and the amount of wear of the drum was obtained from the wear depth of the drum. Focusing on the amount of pin wear, Ti
The amount of wear of the Ti-VN-based coating is slightly reduced as compared with the -N-based coating. On the other hand, focusing on the amount of wear of the drum, Ti
In the case of Ti-VN coating, the amount of wear is remarkably reduced as compared with the case of -N coating, and Ti-V- with V atom% of 45% is used.
With the N-based coating, the amount of wear is suppressed to nearly half that of the Ti-N-based coating.

From the results of the above scuff test and wear test, the Ti-VN coating is superior to the Ti-N coating in seizure resistance, has good initial familiarity, and wears the mating material of the sliding portion. It turned out to be a film that can be suppressed.

[0022]

INDUSTRIAL APPLICABILITY As described above, by coating the sliding surface with the nitride film containing Ti as the main metal component and further containing another metal element, the mating material can be used rather than the conventional Ti-N based film. It is possible to obtain a sliding member which does not wear out, has good initial familiarity, and has excellent sliding characteristics such as wear resistance and seizure resistance.

Claims (1)

[Claims] 1. Titanium, group M (M; chromium, vanadium, zirconium, niobium, molybdenum, hafnium,
Tantalum, one or more metal elements selected from tungsten and aluminum) and nitrogen,
The composition ratio of the metallic elements is M / (Ti + M) = 1 to 1 in atomic% ratio
A sliding member, characterized in that the substrate is coated with a film of 45%.