| 摘要 |
PURPOSE: To prevent the elution of metal ions in inside layers and to assure the fatigue strength of the lowest limit necessary for a sliding surfaces by nitriding the crystal grains of the entire surface of titanium and titanium alloy surfaces, thereby forming a nitriding reaction layers of a specific depth. CONSTITUTION: The nitridation reaction layers of the depth of 5 to 20μm from the surfaces are formed by subjecting the titanium and the titanium alloy to the nitriding treatment to improve the wear resistance thereof. As a result, the formation of the coarser crystal particles of the nitridation treated layers is prevented and the elution of the internal metal ions harmful when the titanium and the titanium alloy are used for implants of living bodies is prevented. The fatigue strength of the lowest limit necessary for the sliding surfaces when the titanium and the titanium alloy are used the sliding parts with this depth of the nitridation treated layers. The nitriding treatment is preferably executed by a gaseous nitrogen refining device having an impurity removing means. H2 SO4 , Mg powder, Ca, etc., are respectively usable for impurities, such as moisture, hydrogen, chlorine and oxygen, etc., as this impurity removing means. |
