Electrochemical studies on the corrosion resistance of Gold 18K and thermo active alloy in artificial sweat in presence of sodium chloride

Abstract

Corrosion resistance of thermo active alloy and Gold 18K alloy immersed in artificial sweat in the absence and presence of 100 ppm of NaCl has been investigated by polarization study and AC impedance spectra. It is observed that corrosion resistance of thermo active alloy and also Gold 18K alloy immersed in artificial sweat in the presence of 100 ppm of NaCl increases. Hence it is concluded that people wearing ornaments made of these two alloys need not worry about the excess of sodium chloride in their sweat. When thermo active alloy is immersed in artificial sweat in the presence of 100 ppm of NaCl, linear polarization resistance value increases from 1760283 Ohm cm2 to 9506106 Ohm cm2 ; corrosion current decreases from 1.845x10-8 to 4.008x10-9 A/cm2 ; charge transfer resistance value increases from 4884 Ohmcm2 to 12210 Ohm cm2 ; impedance value increases from 4.367 to 4.8; double layer capacitance decreases from 1.0442 x10 -9 to 4.1769x10-10 F/cm2 , and phase angle increases from 48.1 to 66.34°. When Gold 18K alloy is immersed in artificial sweat in the presence of 100 ppm of NaCl, linear polarization resistance value increases from 1079199 Ohmcm2 to 2385141 Ohm cm2 ; corrosion current decreases from 4.036x10-8 to 0.1966 x 10 -8A/cm2 ; charge transfer resistance increases from 4291 Ohm cm2 to 48880 Ohm cm2 ; impedance value increases from 4.652 to 5.114; double layer capacitance decreases from 1.189 x10-9 to 1.0434 x10-10 F/cm2 , and phase angle increases from 61 to 88.

Keywords

• corrosion resistance
• thermo active alloy
• gold 18k alloy
• artificial sweat
• nacl
• polarization study
• ac impedance spectra