How to Select Arc Spray Coating Materials for different Anti-corrosive Applications?

Generally, the principle for atmospheric corrosion environment is:

• pH = 7-12 alkaline environment: pure Zn and Zn alloy
• pH = 4-7 acidic environment: Al and Al alloy
• pH = 6-8 neutral environment: Zn-Al alloy

Regarding the bridge and other large steel structures in the ocean atmosphere, industrial city atmosphere and acid rain environment, it is suitable to spray Al and Al alloy coating plus weathering finish top-coat.

Regarding steel structures in the environment of dry area with good quality air, such as television towers and transmission towers, it is appropriate to apply arc spraying with Zn and ZnAl 95/5 alloy.

Regarding steel structures immersing in inland rivers and fresh water, such as river hydraulic gates, volute, draft tube and water tanks, it is better to arc spray ZnAl 85/15 materials plus sealing coating.

Regarding steel structures immersing in seawater, such as tide gates and steel fences, it is superior to arc spray Al and Al alloy (e.g. AlMg5) or ZnAl 85/15 plus anti-erosive sealing material plus anti-erosion surface overlay.

Regarding steel structures in acid, alkali, salt and other chemical corrosion environment, the strategy is to choose Pb, stainless steel (316 & 316L), Ni-Cu alloy (Monel 400), pure Al and Al alloy according to respective corrosive medium that should be resist.

Regarding steel structures in high-temperature oxidization and thermal corrosive environment, how to choose appropriate alloys is on basis of the composition, temperature and other factors of corrosive media. Typical alloys are iron base alloys (e.g. FeCrAl, Cr3C2-FeNi) and nickel base alloys (e,g. NiCrAlY, NiAl, NiCr 80/20, NiCrTi). Cr3C2-FeNi and NiCrTi coatings also possess excellent anti-erosive property. These types of coatings are widely used in metallurgy, petrochemical, thermoelectricity and other industrial fields.