Corrosion and mechanical properties of atomic layer deposited TiO2 coatings on NiTi implants

Abstract

In the case of biomedical NiTi implants staying in the human body not only for a short time, a release of Ni ions from NiTi surface should be prevented because of the poisonous character of Ni. We modified the surface of NiTi plate samples by depositing TiO2 oxide using atomic layer deposition (ALD). We found excellent corrosion properties of the coated NiTi samples, implying that ALD has great potential in depositing protection or biocompatible layer for 3D printing. Additionally, using a mechanical tester installed in the sample chamber of a scanning electron microscope, we were not able to see any tensile-load-induced microcracks in the thin atomic layer deposited TiO2 coating. Whereas the TiO2 layers grown thermally by oxidizing NiTi at temperature around 450 °C contained densely distributed microcracks during loading.