Classification of Thermal Spraying Coatings

According to the classification method drafted by Doctor F. N. Longo, US, the thermal spraying coating can be divided into following types in terms of functions:

(1) Wear-resistant Coating

It contains anti-sticking wear, surface fatigue wear coating and erosion resistant coating. In some cases the coating requirement involves wear-resistance to low temperature (< 538 ºC) wear or high temperature (538 ~ 843 ºC).

(2) Heat-resistant & anti-oxidation Coating

It is usually required in high temperature processes and molten metal processes. The high temperature refers to where oxidizing atmosphere, corrosive gas, erosion and thermal barrier above 843 ºC happen, whilst molten metal refers to the place in which molten zinc, molten aluminum, molten iron and steel and molten copper occur.

(3) Anti-atmospheric-corrosion & Anti-dipping-corrosion Coating

Atmospheric corrosion includes the corrosion caused by industrial, salt and field atmosphere; Dipping corrosion consists of the corrosion caused by drinking fresh water, non-drinking fresh water, hot fresh water, salt water, chemical and food processing.

(4) Conductivity & Resistance Coating

This coating is used for conductivity, resistance and shielding.

(5) Size Restoration Coating

The coating is used for iron-based products like machinable and grindable carbon steel and corrosion-resistant steel, and non-ferrous (nickel, cobalt, copper, aluminum, titanium and their alloys) products.

(6) Mechanical Parts Gap Control Coating

The coating can be ground.

(7) Chemical Corrosion Resistant Coating

Chemical corrosion comprises corrosion of various acids, alkalis, salts, inorganic matter and kinds of organic chemical media.

Of the above functions, coatings closely related to metallurgical industries are wear-resistant coating, heat-resistant & anti-oxidation coating, and chemical corrosion resistant coating.