Ultrasonic Joining of Carbon Fiber Reinforced Thermoplastic and Ti Alloy

In this study we investigated the effect of anodizing process of a titanium plate by phosphoric acid and sulfuric acid (H 3 PO 4 aq. (5wt%) and H2SO4 aq. (5wt%) 27°C 300s for 50V ~ 190V) on the surface morphology in order to enhance the joining strength of a carbon fiber reinforced thermoplastic CFRTP) and the preprocessed titanium plate (CP(Commercially Pure) titanium and $\beta$ titanium alloy) joined by ultrasonic welding. After the process, titanium plate has the small pits with the average diameter of 10~100nm or the large groove over 1 $\mu$ m. The pore diameter grew larger as anodizing voltage increased, and the agglomerated pores appeared over 150V. The welding strength of CFRTP/CP titanium was approximately 3 times higher than one without the chemical process, achieving 4.0MPa in the case of the pre-processing at 100V for 300s.