Effect of Electrolyte Layer Thickness of Potassium Acetate Type Deicing Fluid on Corrosion Behavior of 4130 Steel

A test apparatus was set up and the thickness of electrolyte layer was controlled accurately using E-PTFE waterproof breathable film. The influence of the thickness of 5 mass% potassium acetate type deicing fluid electrolyte layer on the corrosion behavior of 4130 carbon steel for airplane was studied by electrochemical method. The results show that the corrosion processes in this system were mainly controlled by oxygen diffusion on cathode. The dissolution and diffusion of corrosion products under the electrolyte layer had great influence on corrosion rate. The impedance spectra of corrosion system in different thicknesses had one time constant, and the solution resistance decreased with the increase of thickness. When the layer thickness was thin (approximate 30 μm), the corrosion rate was tiny. With the increase of thickness, the corrosion rate increased gently at first, and then rose rapidly. When the thickness was about 200 μm, the corrosion rate reached an extremum and then decreased rapidly. When the electrolyte layer continuously increased in thickness, close to full immersion state, the corrosion rate increased gradually and then turned to be stable.