The effect of titania on the micro-scratch behavior of HA-TiO۲ nanostructured composite coatings fabricated by electrophoretic deposition

چکیده مقاله

In the present study, the HA/TiO2 nanostructured composite coatings with 0, 10 and 20 wt% TiO2 were fabricated by electrophoretic deposition to reduce thermal expansion coefficient mismatch between hydroxyapatite and Ti substrate. Micro-scratch tests in progressive load mode, were examined based on the linear elastic fracture mechanics for evaluation of adhesion strength, tribology and fracture toughness of coatings. The critical loads in micro-scratch test for crack initiation (Lc1) and delamination (Lc2) were increased by the addition of TiO2 content in the coating. The maximum critical scratching distance and normal load were obtained for the HA-20 wt% TiO2 composite coating. According to Hertz theory, the critical contact pressures (Pc1=3.71 GPa and Pc2=5.18 GPa) were obtained for HA-20 wt% TiO2 sample. Moreover, the calculated fracture toughness of coatings was increased by the addition of TiO2. The scratch grooves were characterized by scanning electron microscope (SEM). The phase and structural agents of the coatings were analyzed by X-ray diffraction (XRD) and FT-IR, respectively.