Corrosion Behaviour of Iron in Methanol Solution Containing Formic Acid

摘要

Corrosion behaviours of mild steel wereinvestigated by measurement of corrosion loss and stress corrosioncracking tests in methanol and its solutons containing formic acid.In methanol solution containing 05.% formic acid, corrosion ratewas maximum at the composition of approximately 98% methanolwith 2% water and was minimum at 85 to 90% methanol with 10to 15% of water. General corrosion and pitting corrosion werefound in these solutions. Especially at temperatures of 40 to 50°C,many pits were observed. In methanol solution containing 0.05 and0.5% formic acid, corrosion loss increased proportionally squareroot of immersion time. Addition of acid to 85 to 85.5% methanolwith 14.5% water increased corrosion rate in the order ofhydrochloric acid, formic acid and acetic acid. Sodium chlorideaddition to about 85% methanol solution containing 0.5% formicacid decreased corrosion rate in comparison with non addition.Stress corrosion cracking was not found before 140 hours in U-bend and 3 point bending tests in methanol solution containing formic acid.