Corrosion is an electro-chemical process, which takes place between a metal and the surrounding environment. Producing oxides and other undesirable compounds, corrosion is frequently found in combination with mechanical wear. The corrosion process needs three components: an anode, a cathode and an electrolyte. The anode is the metal subject to the effects of corrosion, the electrolyte acts as the corrosive medium and the cathode, which can be on the same surface or a different surface than the anode, completes the electrical cell.

The three primary methods used to combat corrosion are:

Anodic Protection
Anodic protection for steel is limited to zinc and aluminum coatings. The sacrificial action of these coatings prevents the natural corrosion process from taking place on the substrate.

Cathodic Protection
A cathodic protection for a steel consists usually of a standard stainless steel or a special nickel alloy material. These coatings form a barrier, protecting the substrate material from the environment.

Neutral Protection
Neutral materials, such as aluminum oxide or chrome oxide provide excellent corrosion protection by separating the substrate from the environment. Often, a specially formulated sealant material is used to provide additional protection. Nitriding with subsequent oxidizing forms layers that outperform hard chrome in corrosion applications and improve the corrosion resistance of low alloys steels.

Sulzer Metco has very broad experience in applications where corrosion mechanisms are a concern, and we have developed a large portfolio of coating systems as a result. These solutions range from applications for general mechanical engineering systems to very specialized solutions for industries such as textile machinery, paper and the steel industries.