The Korean Society of Surface Science and Engineering

Polyetheretherketone (PEEK) has been widely utilized in spinal implants owing to its favorable mechanical properties and radiolucency. Nevertheless, its intrinsically bio-inert surface limits direct bone attachment, often resulting in delayed osseointegration. Titanium coating has been proposed as an effective strategy to improve the interfacial bioactivity of PEEK, and among the available coating methods, physical vapor deposition (PVD) offers distinct advantages such as low processing temperature and the ability to produce uniform thin films without thermal degradation of the polymer substrate. This study aimed to evaluate the mechanical adhesion behavior of PVD titanium coatings applied to PEEK surfaces prepared under two different pre-processing conditions: machining (smooth surface) and zirconia bead blasting (rough surface). Adhesion performance was quantitatively assessed through tensile adhesion strength (ASTM F1147-05), shear adhesion strength (ASTM F1044-05), and fatigue shear testing (ASTM F1160-14). The tensile adhesion strength of the machining group was approximately 25% higher than that of the sanding group, whereas shear adhesion strength showed no significant difference between groups. Both surface conditions demonstrated stable performance under 10 million cycles of repeated shear loading without evidence of delamination or particle generation. The results indicate that PVD titanium thin films can establish mechanically stable interfaces on PEEK substrates. The reduced tensile adhesion in the roughened group may be attributed to discontinuities in the deposited thin film and limitations of adhesive layer uniformity required in ASTM-based testing. Considering the inherent characteristics of thin-film deposition under vacuum, clinically optimal roughness levels for osseointegration (Ra 2–3 μm) may still be advantageous when combined with uniform PVD coating. Further studies incorporating additional surface roughness levels, coating parameters, and biological evaluations are warranted to optimize coating strategies for clinical applications.

키워드 PEEK; titanium coating; PVD; adhesion strength; shear strength; fatigue durability; surface roughness; spinal implants.