Sliding system

Patent metadata

Field	Value
Publication number	US-9790447-B2
Application number	US-201514796081-A
Country	US
Kind code	B2
Filing date	Jul 10, 2015
Priority date	Oct 24, 2014
Publication date	Oct 17, 2017
Grant date	Oct 17, 2017

Abstract

[Technical Problem]
An object is to provide a sliding system which can drastically reduce the friction coefficient on a sliding portion by means of a novel combination of a chromium nitride film and a lubricant oil.
[Solution to Problem]
The sliding system according to the present invention includes: a pair of sliding members having sliding surfaces that can relatively move while facing each other; and a lubricant oil that can be interposed between the sliding surfaces facing each other. At least one of the sliding surfaces is formed as a coating surface of a chromium nitride film, and the lubricant oil contains an oil-soluble molybdenum compound that has a chemical structure of a trinuclear of Mo. When the chromium nitride film as a whole is 100 at % (referred simply to as “%”), the chromium nitride film contains 40-65% of Cr and 35-55% of N, and the chromium nitride film has a relative surface area of 15-60% wherein the relative surface area is a surface area ratio of (111) plane to (200) plane obtained when analyzed using X-ray diffraction. The lubricant oil preferably contains 5-800 ppm of the oil-soluble molybdenum compound in a content mass of Mo to the lubricant oil as a whole.

First claim

The invention claimed is:

1. A sliding system comprising:
a pair of sliding members having sliding surfaces that can relatively move while facing each other; and
a lubricant oil that can be interposed between the sliding surfaces facing each other,
wherein at least one of the sliding surfaces comprises a coating surface of a chromium nitride film;
wherein the lubricant oil contains an oil-soluble molybdenum compound that has a chemical structure of a trinuclear molybdenum compound,
wherein, when the chromium nitride film as a whole is 100 at % (referred simply to as “%”), the chromium nitride film contains 40-65% of Cr and 35-55% of N, and the chromium nitride film has a relative surface area of 15-34% wherein the relative surface area is a surface area ratio of (111) plane to (200) plane obtained when analyzed using X-ray diffraction.

2. The sliding system as recited in claim 1 ,
wherein Mo and S are present on the sliding surface of the chromium nitride film, and a ratio of a number of atoms of S to that of Mo is 2 or more when analyzed using X-ray photoelectron spectroscopy (XPS).

3. The sliding system as recited in claim 1 , wherein the chromium nitride film further contains 2-15% of O.

4. The sliding system as recited in claim 1 , wherein the chromium nitride film contains Cr 2 N in addition to CrN.

5. The sliding system as recited in claim 1 , wherein the trinuclear molybdenum compound has a molecular structural skeleton of at least one of Mo 3 S 7 or Mo 3 S 8 .

6. The sliding system as recited in claim 1 , wherein the lubricant oil contains the oil-soluble molybdenum compound with a mass ratio of Mo to the lubricant oil as a whole of 5-800 ppm.

7. The sliding system as recited in claim 1 , wherein, when a detected amount by the XPS is 100 at % as a whole, 0.04 at % or more of Mo is present.

8. The sliding system as recited in claim 1 , wherein, when a detected amount by the XPS is 100 at % as a whole, 0.06 at % or more of Mo is present.

9. The sliding system as recited in claim 8 , wherein Mo and S are present on the sliding surface of the chromium nitride film, and a ratio of number of atoms of S to that of Mo is 2 or more when analyzed using X-ray photoelectron spectroscopy (XPS).

10. The sliding system as recited in claim 1 , wherein the ratio of number of atoms of S to that of Mo is 4 or more when analyzed using X-ray photoelectron spectroscopy (XPS).

11. The sliding system as recited in claim 1 , wherein the ratio of number of atoms of S to that of Mo is 5 or more when analyzed using X-ray photoelectron spectroscopy (XPS).

Assignees

• Toyota Motor Co Ltd

Inventors

• Mori Hiroyuki
• Tohyama Mamoru
• Okuyama Masaru
• Hayashi Keiji
• Ikeda Naoya

Classifications

• C10N2030/43

  Sulfur free or low sulfur content compositions · CPC title

• C10M2201/066

  Molybdenum sulfide · CPC title

• C10N2080/00

  Special pretreatment of the material to be lubricated, e.g. phosphatising or chromatising of a metal · CPC title

• C10N2030/06

  Oiliness; Film-strength; Anti-wear; Resistance to extreme pressure · CPC title

• C10N2010/12

  Groups 6 or 16 · CPC title