I have tested stainless steel sample coated by a layer that claims to improve the hardness of the material without reducing corrosion resistance. After 72 hours of salt corrosion tests, I have found that there was corrosion. The corrosion was on the outside it did not travel beyond the coating layer and SEM analysis confirmed this. So say only the coating material experiences some corrosion and it improves hardness with no corrosion to the base material (Stainless Steel Sample). If this corroded sample comes into contact with another material with no corrosion can it somehow transfer corrosion or encourage corrosion of the other material?