Silane–parylene coating for improving corrosion resistance of stainless steel 316L implant material

The corrosion resistance of a two-layer polymer (silane + parylene) coating, on implant stainless steel was investigated by microscopic observations and electrochemical measurements. Long term exposure tests in Hanks solution revealed that the coating of 2 μm can be successfully used for corrosion protection. However, the addition of H2O2, simulating the inflammatory response of human body environment causes a dramatic destruction of the protective coating. Analysis of the experimental data in terms of circuit models enables proposing a deterioration mechanism. OH radicals formed at the metal surface attack the polymer, thus the deterioration starts from the metal/polymer interface and progress towards the outward surface.

Research highlights
► Two-layer (silane + parylene) coating of 2 μm successfully protects implant grade stainless steel surface against corrosion in body fluid.
► Presence of H2O2 simulating inflammatory response of the body causes a dramatic destruction of the coating.
► Degradation process starts at metal/polymer interface and progress towards the outer surface.