Thermal Spray Coatings
Dr. Max Ulrick Schoop of Zurich is credited with developing the first thermal spray devices in the early 1900’s and while his original spray devices were relatively crude, the coatings produced performed effectively. Today there are a number of thermal spray process commercially available and they all basically involve the projection of molten or semi-molten particles of metal, ceramics, or cermets onto a prepared surface where they adhere and form a continuous coatings of controlled thickness. These coatings are widely used throughout industry whether protecting jet engines from high temperatures to offshore environments, where thermal spray aluminium (TSA) has been proven to offer excellent corrosion protection.
Flame spray, the original process, continuously feeds the coating wire through the centre of an oxy-fuel torch, where molten particles from the tip are projected on to the prepared work piece by the fast moving flame gases. Flame spray can be used to apply all the commonly specified corrosion protection materials such as aluminium or zinc. This process is typically used on the more intricate surface geometries due to its relatively small spray foot-print allowing better control of the coating thickness.
In the Arc Wire process, two oppositely charged wires are continuously fed to the spray pistol where the tips are melted by the resulting electric arc and compressed air is used to project the molten particles. Whilst this process can only spray electrically conductive materials, it does produce the higher quality coatings, and has the advantages of being faster and more suited to automation than flame spray.
Gemini operates both flame spray and arc wire process depending on application and specification requirements, all applied by NORSOK M-501 qualified. Whilst thermal spray coatings are typically used protect assets from corrosion due to their galvanic nature, it should also be remembered that they have other useful properties. Besides being more durable than paint and able withstand higher temperatures, they are also thermally conductive which can aid heat.
