| 主权项 |
1. A sliding member having a sliding surface formed on a surface of a metal base material, the sliding surface having a surface texture that comprises:
a hard part, the hard part being a modified part obtained by subjecting the surface of the metal base material to modification treatment; and a tough part contacting with the hard part, the tough part being a non-modified part that is not subjected to the modification treatment, the tough part having a hardness lower than that of the hard part, and a portion of the hard part that extends below the sliding surface is surrounded on every side by the tough part, wherein
the hard part is either one of: (i) a nitride part subjected to nitridation treatment; (ii) an oxide part subjected to oxidation treatment; (iii) a phase transformation part subjected to heat treatment; or (iv) a size refined part subjected to size refinement treatment for crystal grains;when the hard part is obtained by subjecting the surface of the metal base material to the nitridation treatment or the oxidation treatment, a concentration of nitrogen or oxygen in the hard part is 1 atomic percent (at%) or more;when the hard part is obtained by subjecting the surface of the metal base material to the size refinement treatment, an average crystal grain diameter of the hard part is 400 nm or less; andthe tough part has the same original characteristics as the metal base material before the metal base material is subjected to any of the nitridation treatment, the oxidation treatment, the heat treatment, or the size refinement treatment, the original characteristics including at least a concentration of nitrogen, a concentration of oxygen, a phase, and the average crystal grain diameter. |
