TY - JOUR

T1 - Surface Modification of Additively Manufactured Nitinol by Wet Chemical Etching

AU - Назаров, Денис Васильевич

AU - Рудакова, Аида Витальевна

AU - Борисов, Евгений

AU - Попович, Анатолий

N1 - Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

PY - 2021/12/1

Y1 - 2021/12/1

N2 - Three-dimensional printed nitinol (NiTi) alloys have broad prospects for application in medicine due to their unique mechanical properties (shape memory effect and superplasticity) and the possibilities of additive technologies. However, in addition to mechanical properties, specific physicochemical characteristics of the surface are necessary for successful medical applications. In this work, a comparative study of additively manufactured (AM) NiTi samples etched in H2SO4/H2O2, HCl/H2SO4, and NH4OH/H2O2 mixtures was performed. The morphology, topography, wettability, free surface energy, and chemical composition of the surface were studied in detail. It was found that etching in H2SO4/H2O2 practically does not change the surface morphology,while HCl/H2SO4 treatment leads to the formation of a developed morphology and topography. In addition, exposure of nitinol to H2SO4/H2O2 and HCl/H2SO4 contaminated its surface with sulfur and made the surface wettability unstable in air. Etching in NH4OH/H2O2 results in surface cracking and formation of flat plates (10–20 microns) due to the dissolution of titanium, but clearly increases the hydrophilicity of the surface (values of water contact angles are 32–58°). The etch duration (30 min or 120 min) significantly affects the morphology, topography, wettability and free surface energy for the HCl/H2SO4 and NH4OH/H2O2 etched samples, but has almost no effect on surface composition.

AB - Three-dimensional printed nitinol (NiTi) alloys have broad prospects for application in medicine due to their unique mechanical properties (shape memory effect and superplasticity) and the possibilities of additive technologies. However, in addition to mechanical properties, specific physicochemical characteristics of the surface are necessary for successful medical applications. In this work, a comparative study of additively manufactured (AM) NiTi samples etched in H2SO4/H2O2, HCl/H2SO4, and NH4OH/H2O2 mixtures was performed. The morphology, topography, wettability, free surface energy, and chemical composition of the surface were studied in detail. It was found that etching in H2SO4/H2O2 practically does not change the surface morphology,while HCl/H2SO4 treatment leads to the formation of a developed morphology and topography. In addition, exposure of nitinol to H2SO4/H2O2 and HCl/H2SO4 contaminated its surface with sulfur and made the surface wettability unstable in air. Etching in NH4OH/H2O2 results in surface cracking and formation of flat plates (10–20 microns) due to the dissolution of titanium, but clearly increases the hydrophilicity of the surface (values of water contact angles are 32–58°). The etch duration (30 min or 120 min) significantly affects the morphology, topography, wettability and free surface energy for the HCl/H2SO4 and NH4OH/H2O2 etched samples, but has almost no effect on surface composition.

KW - Additive manufacturing

KW - Biomaterials

KW - Chemical etching

KW - Nitinol

KW - Surfaces

KW - Wettability

UR - https://www.mdpi.com/1996-1944/14/24/7683

UR - http://www.scopus.com/inward/record.url?scp=85121325782&partnerID=8YFLogxK

U2 - 10.3390/ma14247683

DO - 10.3390/ma14247683

M3 - Article

C2 - 34947279

VL - 14

JO - Materials

JF - Materials

SN - 1996-1944

IS - 24

M1 - 7683

ER -