Titanium surface treatment method

A titanium surface treatment method for bonding with a polymer composite which comprises:

• (a) a first etching step wherein the titanium surface is etched by acidic solution;
• (b) a first surface treatment step wherein the titanium surface is treated by ultrasonic wave;
• (c) a second etching step wherein the titanium surface is etched again by acidic solution;
• (d) a second surface treatment step wherein the titanium surface is treated again by ultrasonic wave;
• (e) a first silane coupling treatment step wherein the titanium surface is treated by ultrasonic wave;
• (f) a third surface treatment step wherein the titanium surface is treated again by ultrasonic wave;
• and
• (g) a second silane coupling treatment step wherein the titanium surface is treated by anodic oxidation;
• wherein the first silane coupling treatment step (e) is performed
• in a first silane coupling solution containing
• 10-50 wt % of NaOH, Na2CO3 and NH4NO3,
• mixed at a weight ratio of 3:1:1 and
• a first silane coupling agent
• at a concentration of 0.1-1 wt %,
• wherein the first silane coupling treatment step (e) performs ultrasonic wave for 10-300 seconds at a frequency of 24-100 kHz, at 30-70° C. and at an output of 400 W,
• wherein the second silane coupling treatment step (g) is performed in a second silane coupling solution containing 10-50 wt % of
• NaOH, KOH, Ca(OH)2 and NaHCO3, that are mixed at a weight ratio of 3:1:1:1, and
• a second silane coupling agent at a concentration of 0.1-1 wt %, wherein the second silane coupling treatment step (g) performs the anodic oxidation for 1 to 30 minutes at a current density of 0.1 to 10 A/dm2 using a rectifier for a positive 1 Hz pulse current with durations of 500 ms at 30 to 70° C.