Sliding member and fluid dynamic pressure bearing apparatus
View Patent ↗There is provided a sliding member including: a substrate; and a protective film provided on the substrate, wherein the protective film is composed only of a metal base layer provided on the substrate, a low-hardness diamond-like carbon layer provided as a single layer on the metal base layer, and a high-hardness diamond-like carbon layer provided as a single layer directly on the low-hardness diamond-like carbon layer. The sliding member has the protective film which has excellent frictional wear resistance property and satisfactory adhesion property to the substrate, regardless of having a simple structure.
1. A sliding member comprising:
a substrate; and
a protective film provided on the substrate, the protective film consisting of a metal base layer provided on the substrate, one low-hardness diamond-like carbon layer provided on the metal base layer, and one high-hardness diamond-like carbon layer provided directly on the low-hardness diamond-like carbon layer, wherein
the high-hardness diamond-like carbon layer has a homogenous structure within the high-hardness diamond-like carbon layer,
the low-hardness diamond-like carbon layer has a columnar structure in which a plurality of streaks extend in a thickness direction of the low-hardness diamond-like carbon layer, and
a hardness of the high-hardness diamond-like carbon layer is not less than 28 GPa, and a hardness of the low-hardness diamond-like carbon layer is not more than 17 GPa.
2. The sliding member according to claim 1 , wherein a ratio of a thickness of the high-hardness diamond-like carbon layer with respect to a total of the thickness of the high-hardness diamond-like carbon layer and a thickness of the low-hardness diamond-like carbon layer is 75% to 95%.
3. The sliding member according to claim 1 , wherein both of the high-hardness and low-hardness diamond-like carbon layers do not contain hydrogen.
4. The sliding member according to claim 1 , which is a protective layer on a thrust bearing of a fluid dynamic pressure bearing apparatus.
5. The sliding member according to claim 4 , wherein a groove, along which a fluid used in the fluid dynamic pressure bearing apparatus flows, is formed on a surface of the substrate; and
the protective film is formed in the groove.
6. The sliding member according to claim 1 , which is a protective layer formed on a bearing sleeve of a fluid dynamic pressure bearing apparatus.
7. A fluid dynamic pressure bearing apparatus comprising the sliding member as defined in claim 1 .
8. A spindle motor apparatus of a hard disk drive comprising the fluid dynamic pressure bearing according to claim 7 .
9. A sliding member, comprising:
a substrate; and
a protective film provided on the substrate, the protective film consisting of a metal base layer, a first diamond-like carbon layer which has a columnar structure in which a plurality of streaks extend in a thickness direction of the first diamond-like carbon layer and which is formed on the metal base layer, and a second diamond-like carbon layer which has a homogeneous structure and which is formed on the first diamond-like carbon layer.
10. The sliding member according to claim 9 , wherein a ratio of a thickness of the second diamond-like carbon layer with respect to total of the thickness of the second diamond-like carbon layer and a thickness of the first diamond-like carbon layer is 75% to 95%.
11. The sliding member according to claim 9 , wherein both of the first and second diamond-like carbon layers do not contain hydrogen.
12. The sliding member according to claim 9 , which is a protective layer formed on a bearing sleeve of a fluid dynamic pressure bearing apparatus.
13. The sliding member according to claim 9 , which is a protective layer formed on a thrust bearing of a fluid dynamic pressure bearing apparatus.
14. A fluid dynamic pressure bearing apparatus comprising the sliding member as defined in claim 9 .
15. A spindle motor apparatus of a hard disk drive comprising the fluid dynamic pressure bearing according to claim 14 .