In the thermal arc spray process, the coating material is included in a spray gun. The current set on the thermal / arc spray gun allows an arc to be generated between two wires. The wire must be electrically conductive to provide the arc creation to be established. Then the wire will be dissolved and accelerated onto a substrate material. The high spray velocity will propel molten spray towards the substrate and the deposited material will be solidified to form a coating. Material usage is depending on customer requirements. But, in general, they require zinc, zinc alloy, aluminum, and aluminum alloy. The characteristic of the arc spray gun parameters.
Before this coating is performed, the first level of substrate surface processing is critically important. The substrate surface must be cleaned and blasted using compressed-air abrasive media. This blasting method is the most useful for cleaning of mill-scaled since its efficiency can reach up to 100%; hence, for good adhesion of thermal spray coating.
The Equipment Setup For Thermal Arc Spray Coating Includes Four Major Parts
- Thermal spray gun – to shoot the melted material onto the substrate
- Air compressor – to accelerate melted material
- Abrasive blasting pot – for the garnet area when blasting preparation is performed
- Thermal arc spray machine – to flow coating material by receiving current
Application of thermal spray coating
Thermal spray coating has been used mostly in corrosion protection and wears resistance. Other than the offshore field, some power plants have applied this coating technology for their equipment and machinery such as boiler tubes, gearbox shaft, and crankshaft.
The application of thermal arc spray coating is not only on the steel structure but also can be used on reinforced concrete structures such as bridges and buildings to protect steel rebar. Normally, high alkaline content inside reinforced concrete structure is enough to prevent corrosion damage of steel rebar. This condition can ensure the passivation of the steel surface.