Optimization of laser parameters for improved corrosion resistance of nitinol
K. E. Ch. Vidyasagar, Abhishek Rana, Dinesh Kalyanasundaram
Abstract
Nickel-Titanium (Nitinol) alloy is one of the shape memory alloys with potential applications in biomedical and aerospace industries. However, long-term deployment of nitinol-based alloys in fluid medium leads to corrosion. In an attempt to improve the corrosion resistance, electrochemical studies were performed on laser processed nitinol in the presence of simulated body fluid. Design of experiments technique of central composite design was used to formulate the five levels of the three laser processing parameters for surface texturing including average power, pulse frequency, and laser irradiation per unit area. The output responses such as corrosion potential, corrosion current, and corrosion rate were evaluated using response surface methodology. The linear and nonlinear interaction effects of the processing parameters on the output responses were analyzed. A decrease in the corrosion rate of three orders of magnitude was observed in laser processed nitinol in comparison to pristine nitinol.