Sliding member and method of manufacturing sliding member
To provide a sliding member having improved wear resistance, and a method of manufacturing the sliding member. A femoral head ball according to an aspect of the present disclosure includes a composite ceramic containing alumina and at least one oxide other than alumina. A surface roughness Ra of the sliding surface when the femoral head ball slides against a constituent member constituting an artificial joint is not more than 0.01 μm. The sliding surface includes a plurality of recessed portions each having an opening diameter of not more than 2 μm.
1 . A method of manufacturing a sliding member, the method comprising:
acid-treating a surface of a composite ceramic containing alumina and at least one oxide other than alumina with a strong acid solution to form a recessed portion in the surface, the recessed portion formed in a sliding surface; and
polishing the surface before the acid-treating, wherein
after the polishing, a surface roughness Ra of the surface before the acid-treating is not more than 0.01 μm, and the surface roughness Ra of the surface after the acid-treating is also not more than 0.01 μm, the sliding surface being configured to slide against a constituent member constituting an artificial joint.
2 . A method of manufacturing a sliding member, the method comprising:
acid-treating a surface of a composite ceramic containing alumina and at least one oxide other than alumina with a strong acid solution to form a recessed portion in the surface, wherein
by the acid-treating, at least 10,000 of the recessed portions are formed in a sliding surface per square millimeter, the sliding surface being configured to slide against a constituent member constituting an artificial joint.
3 . The method of manufacturing a sliding member according to claim 2 , comprising polishing the surface before the acid-treating.
4 . The method of manufacturing a sliding member according to claim 1 , wherein the at least one oxide other than alumina comprises zirconia.
5 . The method of manufacturing a sliding member according to claim 1 , wherein the recessed portion formed by the acid-treating is not more than 2 μm in depth from an opening to a bottom.
6 . The method of manufacturing a sliding member according to claim 1 , wherein the strong acid solution is a hydrochloric acid aqueous solution, a sulfuric acid aqueous solution, or a nitric acid aqueous solution.
7 . The method of manufacturing a sliding member according to claim 6 , wherein, in the acid-treating, the surface is brought into contact with the hydrochloric acid aqueous solution for no less than 5 minutes.
8 . The method of manufacturing a sliding member according to claim 6 , wherein, in the acid-treating, the surface is brought into contact with the hydrochloric acid aqueous solution for no less than 30 minutes.
9 . The method of manufacturing a sliding member according to claim 6 , wherein, in the acid-treating, the surface is brought into contact with the hydrochloric acid aqueous solution for no less than 150 minutes.
10 . The method of manufacturing a sliding member according to claim 1 , wherein the composite ceramic contains 65 to 96 wt % of alumina, and from 4 to 34.4 wt % of zirconia.
11 . The method of manufacturing a sliding member according to claim 1 , wherein the composite ceramic contains at least 0.20 mass % of SiO2, at least 0.22 mass % of TiO2, and at least 0.12 mass % of MgO.
12 . The method of manufacturing a sliding member according to claim 11 , wherein the total content ratio of SiO2, TiO2, and MgO is from 0.6 to 4.5 mass %.
13 . The method of manufacturing a sliding member according to claim 1 , comprising grinding the composite ceramic before the polishing.
14 . The method of manufacturing a sliding member according to claim 13 , wherein, in the grinding, the composite ceramic is ground to a shape of a femoral head ball.
15 . A method of manufacturing an artificial hip joint, wherein the artificial hip joint is manufactured by combining a sliding member manufactured by the manufacturing method according to claim 1 , an acetabular cup, and a femoral stem.