CORROSION INHIBITION OF CASEIN AS A NATURAL PROTEIN FOR 316L STAINLESS STEEL IN SIMULATED BODY FLUID

The importance of biomaterials is increased steadily with the augmentation of population and aging. In this research, casein, a protein present in milk, used to modify the 316L stainless steel (316L SS) alloy surface, used in medical application, against corrosion in the corrosive body fluid. Due to the presence of hetero-atoms in its moiety, casein has the ability to form a protective thin layer. Self-assembled monolayers (SAMs) technique is a common tool providing a well ordered thin film on the metallic surface. Casein was assumed to form SAMs on the 316L SS surface and the corrosion inhibition efficiency was examined electrochemically. The results proved the formation of SAMs and displayed that casein reduce the corrosion rate and serves as a mixed type inhibitor. The inhibition efficiency is increased by increasing the casein’s concentration and immersion time in the casein’s solution. A maximum inhibition efficiency obtained at 1000 ppm with immersion time equals 120 minutes. Further modification is undertaken to increase the inhibition efficiency.