Melatonin as an Accelerating Agent for Phosphate Chemical Conversion Coatings on Mild Steel with Enhanced Corrosion Resistance

Abstract

Melatonin (MEL), as a new accelerating agent, is applied for phosphate chemical conversion coating on mild steel. Scanning electron microscopy has been applied to observe the morphology of phosphating crystals, showing that the incorporation of MEL results in more dense and uniform phosphate coatings. Electrochemical impedance spectroscopy and potentiodynamic polarization are performed to evaluate corrosion resistance of phosphate coatings. The results show that the corrosion rate of blank phosphate coating is 5.64 mpy, while the corrosion rate of phosphate coating accelerated with 1.25 g l −1 MEL is reduced to 0.04 mpy. In addition, the dry friction test shows that friction coefficient of the phosphate coatings with the introduction of MEL is decreased to 0.3 compared to 0.6 of the blank one, proving that MEL also reduces the friction resistance of phosphate coatings along with improved corrosion resistance.

Anti-corrosion applications of 2D transition metal based layered materials

“…The metal comes into contact with the electrolyte solution to form a corroded primary battery, resulting in the destruction of the metal materials and the inability to do any useful work for the outside world. 87 Electrochemical corrosion includes three processes, the anodic process, cathodic process, and current loop. Among them, the anode process is that a metal substrate dissolves when it comes into contact with the corrosive medium (M → M n + + n e − ), and then enters the media in the form of metal ions.…”

PDA@α-ZrP/SiO2 incorporated phosphate coating with enhanced corrosion resistance and friction resistance

“…The formula of phosphating bath was based on our previous work. 29 Different concentrations of PDA@a-ZrP/SiO 2 (0.25 g L −1 , 0.55 g L −1 , 0.85 g L −1 ) were introduced into the phosphating bath and ultrasonicated at room temperature for 30 min to obtain the uniform phosphating solution. The pretreated Q235 substrates were placed in the prepared phosphating bath and phosphating at 50 °C for 30 min.…”