Characteristics and mechanism of surface damage of hybrid ceramic ball bearings for high-precision machine tool

• Si-contain hard particles detached from surface of the ceramic balls were pressed into the race-way of the bearing rings under the cyclic contact stress. • Metamorphic layer forms under the rolling cyclic stress and thickens gradually. • The micro-cracks can initiate in metamorphic layer, and propagate to the surface, which result in spalls. For investigating surface damage mechanism, three types of hybrid ceramic ball bearings, under the same conditions, were installed and tested in the same spindle of a bearing test bench for comparison. Then the damage characteristic morphology and microstructure at different operation times were systematically characterized using white-light interferometer, scanning electron microscope, and transmission electron microscope. Meanwhile, the damage mode and related microstructure deterioration around the upper layer of surface have been revealed for these three hybrid ceramic ball bearings. Finally, the results present that the surface fatigue behavior is different from the traditional rolling contact fatigue behavior, since the ceramic ball is almost twice as hard as that of the bearing steel. And a large amount of micropits can been found on the surface of the raceways due to the pressing by hard particles detached from the surface of the ceramic balls. Therefore, this surface damage may result in performance degradation of the precision bearing of the machine tool during industrial ultra-precision machining.