Corrosion Resistance of Pure Titanium Fabricated by Laser Rapid Forming

Objectives: To investigate the feasibility of laser rapid forming (LRF) titanium for medical and dental implant materials, the corrosion resistance of LRF Ti was evaluated in this study. Methods: The titanium specimens were processed by LRF from pure titanium powders. Electrochemical tests, static immersion test and stress-corrosion test were used to evaluate the corrosion behavior of LRF Ti. The influence of fluoride and pH value on the corrosion resistance of LRF Ti was also investigated. Results: In four electrolytes, which include artificial salivas, 1% lactic acid solution, 2％ NaF artificial saliva (pH=7) and 2％NaF artificial saliva (pH=3)，the amounts of Ti ions released from LRF Ti samples(62ng/ml, 302ng/ml, 24.7µg/ml and 156.7µg/ml) were smaller than TA2 (66.1ng/ml, 353ng/ml, 33.1µg/ml and 295.7µg/ml) respectively; The corrosion products were Na3TiF6. The greatest amounts of metal ion release were observed in 2% NaF artificial saliva (pH=3). LRF Ti had less corrosion products and pitting corrosion than TA2 in stress-corrosion test. In artificial saliva, 2％NaF artificial saliva(pH=7) and 2％NaF artificial saliva (pH=3), the free circuit potential (Ecorr) of LRF Ti (－469mV,－925mV and－943mV) were higher than those of TA2 (－555mV,－943mV and－956mV);the values for current density of LRF Ti (2.14×10-6 Acm-2, 2.65×10-6 Acm-2 and 4.51×10-6 Acm-2) were lower than those of TA2 (2.18×10-6Acm-2, 4.49×10-6Acm-2 and 6.63×10-6Acm-2).The film resistance（2.77×106Wcm2, 3.41×105Wcm2 and 4.3×104Wcm2）and transfer resistance （6.71×104Wcm2, 2028Wcm2 and 4.4×103Wcm2）of LRF Ti were higher than those of TA2 （1.42×106Wcm2, 6.65×104Wcm2and 16.93Wcm2）and（236.9Wcm2, 44.1Wcm2and 2.56×103Wcm2） respectively. Conclusions: Low pH value and fluoride in the solution could accelerate Ti iron release; LRF Ti had more corrosion resistance than TA2.