Development of Titanium Alloys with Corrosion Resistance in Aqueous Fluoride Solutions

摘要

Titanium has been selected as the materials for several dental equipments because of its excellent mechanical properties, biocompatibility, and corrosion resistance to chloride solutions. Besides,fluoride is well documented as an anticariogenic agent. However,Ti has a nature to dissolve in aqueous fluoride solutions,so that there have been some reports regarding corrosion problem of the titanium dental devices. One of the countermeasure to the problem is to develop a new titanium alloy resistant to corrosion in the fluoride solutions. Our research group has tried to develop new titanium alloys with corrosion resistance in the fluoride solutions in the following concept: A lot of metal fluorides are soluble into aqueous solution, but some of them are very hard to dissolve. In the case that those metals are able to be alloyed to titanium, the Ti alloy is expected to perform excellent corrosion resistance due to forming almost insoluble film of the metal fluoride on the surface, like passivation. On the basis of the concept,we successfully tried to develop Ti-Mg,Ti-Ca and Ti-Ni alloys resistant to corrosion in the fluoride solution. The aim of this paper is to introduce the details of the corrosion behavior of the newly developed Ti alloys in some fluoride solutions.