It could be argued that this is not applicable to all situations. Depending on choice of coating system and environment the life expectancy can be well in excess of 20 years with no maintenance. This method is generally regarded as providing superior corrosion protection than galvanising, plating and painting without excessive cost penalties. Cathodic Coatings Cathodic coatings are those which comprise a coating metal which is cathodic with respect to the substrate. A stainless steel or nickel alloy coating would be cathodic to a steel base.
Cathodic coatings can provide excellent corrosion protection.
There is a very wide choice particularly for steel base materials ranging from stainless steel to more exotic materials like tantalum to cater for the more extreme corrosive environments. However, an outstanding limitation of such coatings is that they must provide a complete barrier to the substrate from the environment. If the substrate is exposed to the corrosive environment, the substrate will become the anode and corrosion will be dramatically accelerated resulting in spalling of the coating. Generally, sealing of these coatings is always recommended. Thick coatings will provide better protection than thin coatings.