Study of corrosion behavior of biocompatible porous monolithic material based on titanium nickelide

Introduction: Corrosion resistance is one of the most important requirements for medical devices, as it determines the service life of the material. The aim of this work is to study the corrosion resistance of new biocompatible porous monolithic materials based on titanium nickelide (TiNi), with a different ratio of the reaction additive in the powder system (TiNi:(Ti-Ni)).
Materials and methods: Porous monolithic samples consisting of a monolithic TiNi plate with a porous powder surface were used as the studied material. The surface was powder mixture A–B, where mixture A was (5%Ti+0.5%Ni+TiNi), with exothermic additive B (Ti+Ni) in various ratios: TiNi (1-1), TiNi (1-0.75), TiNi (1-0.5). Sintering was carried out at a temperature of 1100 ℃ and was held for 15 minutes in an electric vacuum furnace. To homogenize the surface, the studied samples were subjected to electron beam treatment. The determination of corrosion resistance was carried out using voltammetry, with a linear potential sweep in a physiological solution.
Results: According to the data obtained from the electrochemical studies, it was established that the rate of corrosion is influenced by the amount of an exothermic additive. The lowest corrosion rate was observed in the TiNi with the highest content: the value of the corrosion rate of the TiNi sample (1-1) was about 2.5 times less than in TiNi (1-0.5). Microscopic analysis showed the presence of local fractures on the surface of the material after electrochemical tests, including cracks and pitting. The porous areas of the material were mainly corroded; therefore, the corrosion rate increases with a decrease in the amount of the exothermic additive.
Conclusions: As a result of the work performed, it is shown that an increase in the proportion of exothermic additives leads to an increase in the corrosion resistance parameters of porous monolithic materials based on TiNi.