Oxidation kinetics and oxygen permeability of the NiTiCu biomaterials

Abstract

The oxidation kinetics of NiTiCu alloys were investigated by thermogravimetric analysis (TGA). The oxidation kinetics followed a linear dependence of weight gain when indicated a diffusion controlled mechanism with various activation energies ranging from 157.569 to 25.123 kJ/mol. It is observed in SEM micrographs that TiO₂ oxides are formed between grain boundaries and inside of the grains. The morphology of the oxides is non-uniformly distributed into the grain boundaries. The oxygen permeability dependence of temperature of the alloys was also investigated. The increase in Ti content in the alloys leads to significant enhancement of the oxygen permeability and the oxygen transport increases in the sequence S1 < S2 < S3 <S4.