Effect on PEEK/Graphite Film for Raceway Surface of PEEK Hybrid Ball Bearings with Surface Crack

To clarify effect on the composite film layer of PEEK and graphite in PEEK hybrid radial alumina ball bearings with surface fatigue cracks, rolling contact fatigue tests were performed by using the PEEK bearing’s inner rings with the surface cracks in the dry and water conditions. When applied load and rotational frequency of the bearing were 98 N and 600–1400 min−1, the number of fatigue cycles of the PEEK hybrid bearings reached 1.0E6 cycles. The PEEK composite film containing nano-sized graphite particle covered the surface cracks on the PEEK ring’s raceway after the tests. In addition, friction heat and cyclic compression caused the plastic flow in the composite film layer of PEEK and graphite. Due to effect of the PEEK/graphite film, the fusion of the cracks on the raceway surface of the PEEK inner ring occurred. The accumulation layer of PEEK/graphite film reduced the surface defects such as surface cracks on the raceway of PEEK inner ring, which improved the bearing’s performance.