(A, B) SEM images of surface morphology of PEEK, (C, D, E) SEM images of surface morphology of CSNPK, (F) SEM images of cross-sectional of CSNPK, (G) EDS of PEEK, (H) EDS of CSNPK. EDS = energy-dispersive spectroscopy; PEEK = polyetheretherketone; SEM = scanning electron microscope.