CORROSION BEHAVIOR OF NEW ΒETA TYPE TITANIUM ALLOY, TI-29NB-13TA-4.6ZR (TNTZ) IN FUSAYAMA-MEYER ARTIFICIAL SALIVA SOLUTION

Abstract

In order to know precisely the corrosion behavior of a new developed β type titanium alloy Ti-29Nb-13Ta-4.6Zr (TNTZ) and ordinary titanium alloy Ti-6Al4V (for comparison) in oral cavity environment, corrosion rate of these alloys in an artificial saliva solution was then investigated. Corrosion measurement was conducted in 600 ml solution of Fusayama-Meyer artificial saliva containing of 0,4 g NaCl, 0.4 g KCl, 0.795 g CaCl2.2H2O, 0.69 g NaH2PO4, and 1 g urea using a potentiostat model (VERSA studio-200) controlled by a personal computer. The solution was maintained at pH 5.2 and 37oC to imitate oral cavity condition. After corrosion test, specimen surfaces were observed by SEM, EDX and XPS. The result show that the averaged corrosion rate of TNTZ and Ti-6Al-4V is 4.5×10-9 mmy-1 and 6.4×10-8 mmy-1 , respectively. This indicates that the corrosion resistance of TNTZ is relatively high, and it is better than that of Ti6Al-4V. This is due to the formation of a multiple layer of Ti, Nb and Zr oxides in the surface of TNTZ. However, formation of micro-pitting corrosion is more intense in TNTZ due mainly to the alloying elements segregation and the presence of high impurities. It is recommended that, therefore, an intense homogenizing process is neccessary to apply in TNTZ for homogenizing the elemental distribution and, subsequently, for minimizing pitting corrosion attack. Having low pitting corrosion attack is an important thing for dental application in order to reduce stress concentration and crack initiation, and then to avoid mechanical failure during application.

Keywords

• Artificial saliva
• Corrosion rate
• Dental material
• Fusayama-Meyer
• Titanium