Effect of Temperature on the Corrosion Resistance of Ni5Al Coating Deposited by Electric Arc in 3.5% NaCl Solution

Abstract

The electrochemical behavior of the Ni5Al coating deposited by an electric arc was evaluated. Its behavior was evaluated in a saline solution as a function of temperature (20 °C, 40 °C, and 60 °C). The variation as a function of time of the Ni5Al coating’s values of open circuit potential, linear polarization resistance, and the evolution of its electrochemical impedance spectra were analyzed. With this deposition technique, the rapid formation of thick coatings is achieved, which reduces the presence of interconnected porosity. Even though the microstructural characteristics showed the presence of trapped oxides, the electrochemical measurements carried out showed excellent corrosion resistance of the coating. The coating quickly develops a passive layer that allows it to rapidly reach thermodynamic equilibrium with the corrosive medium.

Electrochemical Behaviour of an Au-Ge Alloy in an Artificial Saliva and Sweat Solution

“…The Bode magnitude (Figure 3b) showed that, in all the measurements in the low frequency's region, the high impedance values (log Z~4-5) for the tested alloys suggested a good corrosion resistance. The lowest impedance value was registered for the immersion time of 24 h. Furthermore, it should also be noted that, in the Bode absolute (Figure 3b) at high frequencies, for an immersion time of one hour, the modulus of impedance was in a decreasing trend, in contrast to the more or less constant modulus of impedance for other immersion times, which is characteristic behaviour based on the literature [26][27][28]. The non-constant behaviour of the constant modulus at high frequencies certainly confirms that, after one hour in artificial sweat, the film formed on the Au-Ge alloy surface was still rough and porous [23].…”