The corrosion properties of Al/Al2O3 multilayered coatings on CK45 steel deposited by IBAD

For the purpose of providing corrosion protection, multilayered Al/Al2O3 coatings were deposited on CK45 steel by an Ion Beam Assisted Deposition (IBAD) facility. Five kinds of multilayered coatings with overall thickness of 3 μm were made in the experiment, and 0.1 μm graded Al2Ox (x<3) layers were formed between the Al and Al2O3 layers instead of sharp Al/Al2O3 interface. The coating structure and composition were examined with RBS and AES measurement; and the corrosion behavior was determined by potentiodynamically controlled current–potential measurements under conditions of uniform corrosion and pitting corrosion attack. The results show that these multilayered coatings can give good protection to the steel substrate, the corrosion current density decreases three to four orders. Also, the protection ability depends on the coating structure and composition when the overall thickness was fixed.