Effect of electrolyte solutions on the electrochemical dissolution behavior of additively manufactured Hastelloy X superalloy via laser solid forming

Conductive TiCxO1–x solid solutions were prepared by carbothermic reduction of titanium dioxide. Studies were focused on the possibility of electrochemically dissolving TiCxO1–x in NaCl–KCl molten salt. The tail-gas from the anode was monitored during the electrolysis. It was discovered that carbon monoxide (CO) or carbon dioxide (CO2) gases were generated, with the process being dependent upon the consumption of the TiCxO1–x solid solution anode materials. Furthermore, a series of electrochemical methods was used to investigate the valence state of titanium ions dissolved into molten salt when electrolyzing TiCxO1–x solid solutions. A significant result was that titanium ion species dissolved from the TiCxO1–x solid solutions, and this is changed between Ti2+ and Ti3+ depending on the electrochemically dissolving potentials. The significant result discovered in this paper will be potentially beneficial in the preparation of high-purity titanium by electrorefining TiCxO1–x solid solutions.

Download Full-text

Study of the Electrochemical Dissolution Behavior of Nitinol Shape Memory Alloy in Different Electrolytes for Micro-ECM Process

10.21203/rs.3.rs-1077024/v1 ◽

2022 ◽

Author(s):

Abhijeet Sethi ◽

Biswesh Ranjan Acharya ◽

Partha Saha

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Electrochemical Machining ◽

Linear Sweep Voltammetry ◽

Dissolution Behavior ◽

Electrochemical Dissolution ◽

Machining Performance ◽

Micro Ecm ◽

Micro Features ◽

Lower Depth

Abstract Nickel-Titanium alloy (Nitinol) is an excellent shape memory alloy (SMA) for Micro electro-mechanical systems (MEMS) particularly in biomedical applications owing to its three excellent features like shape memory effect (SME), superelasticity, and biocompatibility. The fabrication of micro features on Nitinol SMAs through conventional machining has been challenging due to its temperature-dependent material transformation properties. Micro electrochemical machining (micro-ECM), a nonconventional machining method for conductive material irrespective of strength and hardness has the potential for microfeature fabrication on Nitinol. This study presents the investigation on electrochemical dissolution behavior of Nitinol in different electrolytes for micro-ECM. The influence of electrolytes on the nature of dissolution of Nitinol has been studied by fabricating microchannels in three levels of parameters containing applied voltage and electrolyte concentration. The first three electrolytes were all aqueous neutral electrolytes i.e. sodium chloride (NaCl), sodium nitrate (NaNO3), and sodium bromide (NaBr). For profound analysis of dissolution behavior and its influence on machining performance, potentiodynamic polarization (PDP) tests of Nitinol were performed in aqueous NaCl, aqueous NaNO3, and aqueous NaBr solutions. The PDP tests that are conducted here are cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The three aqueous solutions were utilized for microchannel fabrication in Nitinol through micro ECM in three levels of parameters out of which aqueous NaNO3 was successful in fabricating microchannel. Then nonaqueous electrolyte of ethylene glycol-based NaNO3 has been used to fabricate microchannels with lower depth overcut (DOC), width overcut (WOC), and length overcut (LOC) with respect to aqueous NaNO3 electrolyte.

Download Full-text