The effect of the temperature of the aqueous sodium chloride solution on the corrosion resistance of amorphous cobalt alloys

Temperature significantly affects the rate of corrosion of metals. With an increase in temperature, the oxidation processes of metals proceed much faster, despite the decrease in their thermodynamic potential. The relationship between the rate of corrosion and temperature can be complicated or violated if the structure or other properties of the metal or the film formed on it changes with a change in temperature. In most cases, temperature has a significant effect on the rate of electrochemical corrosion of metals, as it changes the rate of diffusion, overvoltage of electrode processes, the degree of anodic passivity, the solubility of the depolarizer (for example, oxygen) and secondary corrosion products. The properties of amorphous metal alloys (AMS) based on cobalt depend significantly on the nature and amount of alloying applications. Additions of Mn to alloys of the Co–Fe–Si–B system are very important. At a low Mn content (up to 4 at. %), the crystallization temperature remains practically unchanged, and the Curie temperature decreases with increasing Mn content. Since cobalt alloys are increasingly being used, there is a need to test them for corrosion resistance in various aggressive environments, in particular, in a reference solution of sodium chloride at different temperatures. Various electrochemical methods (potentiometry, voltammetry) investigated the corrosion resistance of ribbon amorphous alloys Co 75,5 Fe 4,6 Si 6,0 B 16,7 ; Co 73,6 Fe 3,2 Mn 3,2 Si 5,0 B 15,0 ; Co 73,2 Fe 4,3 Mn 0,5 Si 5,3 B 16,7 ; Co 73,0 (Fe,Ni,Mo,Mn) 5,7 (Si,B) 21,3 ; Co 73,3 (Fe,Ni,Mo,Mn) 5,7 (Si,B) 21,0 in an aqueous solution of NaCl at a temperature of (293–333) K. The dependence of the corrosion resistance of amorphous alloys on the elemental composition and the temperature of the aggressive environment was established. It was found that at the initial moment of contact with a 0.5 M aqueous solution of sodium chloride at higher temperatures, the alloys are passivated. The outer surface of strip alloys is characterized by lower corrosion resistance. Keywords: amorphous metal alloys, cobalt, corrosion resistance, temperature.