US-20260126079-A1 - SLIDING MEMBER AND MANUFACTURING METHOD OF SLIDING MEMBER

US20260126079A1US 20260126079 A1US20260126079 A1US 20260126079A1US-20260126079-A1

Abstract

A sliding member includes a base member and a solid lubricant film disposed to cover the base member. The solid lubricant film is composed of molybdenum disulfide in which a sulfur-to-molybdenum content ratio is 1.33 or less. The molybdenum disulfide constituting the solid lubricant film may contain 11 atomic percent or more of carbon.

Inventors

Nobuyuki Otake

Assignees

DENSO CORPORATION
TOYOTA JIDOSHA KABUSHIKI KAISHA
MIRISE Technologies Corporation

Dates

Publication Date: 20260507
Application Date: 20251016
Priority Date: 20241106

Claims (6)

1 . A sliding member comprising: a base member; and a solid lubricant film disposed to cover the base member, wherein the solid lubricant film is composed of molybdenum disulfide in which a sulfur-to-molybdenum content ratio is 1.33 or less.
2 . The sliding member according to claim 1 , wherein the molybdenum disulfide constituting the solid lubricant film contains 11 atomic percent or more of carbon.
3 . The sliding member according to claim 1 , wherein the solid lubricant film does not have a reflection peak at an incident angle of 7.189° in X-ray diffraction measurement using Cu Kα radiation.
4 . The sliding member according to claim 1 , wherein the base member has an aluminum oxide coating film on an outermost surface of the base member, and the solid lubricant film is disposed on the aluminum oxide coating film.
5 . A manufacturing method of a sliding member that includes a base member and a solid lubricant film disposed to cover the base member and composed of molybdenum disulfide in which a sulfur-to-molybdenum content ratio is 1.33 or less, the manufacturing method comprising: forming the solid lubricant film by an atomic layer deposition method using an organic material having a tertiary-butyl group as a sulfur-containing raw material.
6 . The manufacturing method according to claim 5 , wherein the solid lubricant film is formed at a temperature equal to or lower than a decomposition temperature of the organic material.

Description

CROSS REFERENCE TO RELATED APPLICATION The present application claims the benefit of priority from Japanese Patent Application No. 2024-194492 filed on Nov. 6, 2024. The entire disclosure of the above application is incorporated herein by reference. TECHNICAL FIELD The present disclosure relates to a sliding member and a manufacturing method of a sliding member. BACKGROUND Sliding members made of molybdenum disulfide, which possesses self-lubricating properties, have been conventionally known in various forms. SUMMARY A sliding member according to an aspect of the present disclosure includes a base member and a solid lubricant film disposed to cover the base member. The solid lubricant film may be composed of molybdenum disulfide in which a sulfur-to-molybdenum content ratio is 1.33 or less. BRIEF DESCRIPTION OF DRAWINGS Objects, features and advantages of the present disclosure will become apparent from the following detailed description made with reference to the accompanying drawings. In the drawings: FIG. 1 is a cross-sectional view showing a schematic configuration of a sliding member according to an embodiment of the present disclosure; FIG. 2 is a cross-sectional transmission electron microscope (TEM) image of the vicinity of an interface between an aluminum oxide coating film and a solid lubricant film in the configuration shown in FIG. 1; FIG. 3 is a cross-sectional TEM image of the vicinity of an interface between an aluminum oxide coating film and a solid lubricant film in a comparative example; FIG. 4 is a graph showing a change in the coefficient of friction over the sliding duration in the comparative example; FIG. 5 is a graph showing a sliding cross-sectional profile in the comparative example; FIG. 6 is a graph showing a change in the coefficient of friction over the sliding duration in Example; FIG. 7 is a graph showing a sliding cross-sectional profile in an example; FIG. 8 is a graph comparing X-ray diffraction intensity patterns of the example and another comparative example; FIG. 9 is a graph showing the relationship between the sulfur-to-molybdenum content ratio (S/Mo) and the carbon concentration; FIG. 10 is a graph showing the relationship between the adhesion strength and the carbon concentration in the solid lubricant film; and FIG. 11 is a graph showing the dependence of carbon concentration in the solid lubricant film on the film formation temperature. DETAILED DESCRIPTION A sliding member according to a related art includes a base member and a sliding layer formed on at least a sliding surface of the base member. The sliding layer contains molybdenum disulfide. The sliding layer consists of a first sliding layer formed on the base member and a second sliding layer laminated on the first sliding layer. The first sliding layer contains 10 atomic percent or less of a metal element and/or a compound of a metal element, when the total is set to 100 atomic percent. The metal element is at least one selected from a group consisting of Ti, Cr, W, Zr, and V. The second sliding layer does not contain such metal elements and/or compounds of metal elements. When the first sliding layer contains the metal elements or the compounds of metal elements, a decrease in the strength of the first sliding layer and delamination from the base member are suppressed. Since the second sliding layer does not contain metal elements or compounds of metal elements, the second sliding layer is a soft layer with lower hardness compared to the first sliding layer. Therefore, the second sliding layer exhibits high conformability to the mating material during sliding. Molybdenum disulfide has a layered crystal structure along the (001) planes, and delamination readily occurs along these planes. Therefore, for example, when the (001) planes are oriented perpendicular to the load direction, delamination occurs, whereas if the (001) planes are oriented parallel to the load direction, delamination can be suppressed. However, in general, the (001) planes in the sliding layer are oriented in random directions, making it difficult to achieve complete alignment in a single direction and, consequently, to sufficiently suppress delamination. Furthermore, when the load direction and the sliding direction are not the same, frictional force is applied in the sliding direction, so even if delamination is suppressed in the load direction, delamination may occur in the sliding direction. A sliding member according to a first aspect of the present disclosure includes a base member and a solid lubricant film disposed to cover the base member. The solid lubricant film is composed of molybdenum disulfide in which a sulfur-to-molybdenum content ratio is 1.33 or less. A manufacturing method according to a second aspect of the present disclosure is a manufacturing method a sliding member that includes a base member and a solid lubricant film disposed to cover the base member, and the solid lubricant film is composed of molybdenum disu